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The Impact of Rate of Initial Weight Loss on Long-Term Success in the Treatment of Obesity

Permanent Link: http://ufdc.ufl.edu/UFE0022023/00001

Material Information

Title: The Impact of Rate of Initial Weight Loss on Long-Term Success in the Treatment of Obesity Does Slow and Steady Win the Race?
Physical Description: 1 online resource (58 p.)
Language: english
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: obesity
Clinical and Health Psychology -- Dissertations, Academic -- UF
Genre: Psychology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Controversy exists regarding rate of initial weight loss and long-term success in weight management. Some theorists contend that a rapid rate of initial loss may result in poorer long-term success and that a slow, gradual decrease may lead to better maintenance of lost weight and a superior long-term outcome. We examined this question in the context of a randomized trial of lifestyle treatment in which participants were encouraged to reduce their intake so as to achieve a weight loss of 0.45 to 0.91 kg/week (i.e., 1 to 2 lb/week). We classified participants based on their rate of weight loss during the first month of treatment as FAST ( > 0.68 kg/week > 1.5 lb/week, n =55), MODERATE ( > 0.23 and < 0.68kg/week > 0.5 and < 1.5 lb/week, n = 96) and SLOW ( < 0.23kg/week < 0.5 lb/week, n = 79) losers. These groups were drawn from a sample of middle-aged (mean = 59.3 yr) obese women (mean BMI = 36.8) who participated in a six-month lifestyle intervention that was followed by one year of extended care. The three groups did not differ at baseline with respect to age, weight, BMI, fitness, nutritional intake, or physical activity patterns. The FAST, MODERATE, and SLOW groups differed significantly from each other with regard to net mean weight change at six months (-13.9, -9.6, and -.9kg, respectively, ps < .001) and at 18 months (-11.5, -7.8, and -4.8 kg, respectively, ps < .05). No significant differences in weight regain between 6 and 18 months were found among groups (2.5, 1.8, 1.1 kg, respectively). Odds ratios indicated the FAST group was 5.5 times more likely to achieve a 10% weight loss at 18 months than the SLOW group (58.2 vs. 20.3%), and the MODERATE group was 2.5 times more likely than the SLOW group (38.5 vs. 20.3%). Within the context of lifestyle treatment, these results suggest that there were both short- and long-term advantages to a fast rate of initial weight loss and that those who lost weight quickly were not more susceptible to relapse. These findings suggest that a high rate of initial weight loss is associated with long-term success in weight management.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis: Thesis (M.S.)--University of Florida, 2008.
Local: Adviser: Perri, Michael G.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2010-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022023:00001

Permanent Link: http://ufdc.ufl.edu/UFE0022023/00001

Material Information

Title: The Impact of Rate of Initial Weight Loss on Long-Term Success in the Treatment of Obesity Does Slow and Steady Win the Race?
Physical Description: 1 online resource (58 p.)
Language: english
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: obesity
Clinical and Health Psychology -- Dissertations, Academic -- UF
Genre: Psychology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Controversy exists regarding rate of initial weight loss and long-term success in weight management. Some theorists contend that a rapid rate of initial loss may result in poorer long-term success and that a slow, gradual decrease may lead to better maintenance of lost weight and a superior long-term outcome. We examined this question in the context of a randomized trial of lifestyle treatment in which participants were encouraged to reduce their intake so as to achieve a weight loss of 0.45 to 0.91 kg/week (i.e., 1 to 2 lb/week). We classified participants based on their rate of weight loss during the first month of treatment as FAST ( > 0.68 kg/week > 1.5 lb/week, n =55), MODERATE ( > 0.23 and < 0.68kg/week > 0.5 and < 1.5 lb/week, n = 96) and SLOW ( < 0.23kg/week < 0.5 lb/week, n = 79) losers. These groups were drawn from a sample of middle-aged (mean = 59.3 yr) obese women (mean BMI = 36.8) who participated in a six-month lifestyle intervention that was followed by one year of extended care. The three groups did not differ at baseline with respect to age, weight, BMI, fitness, nutritional intake, or physical activity patterns. The FAST, MODERATE, and SLOW groups differed significantly from each other with regard to net mean weight change at six months (-13.9, -9.6, and -.9kg, respectively, ps < .001) and at 18 months (-11.5, -7.8, and -4.8 kg, respectively, ps < .05). No significant differences in weight regain between 6 and 18 months were found among groups (2.5, 1.8, 1.1 kg, respectively). Odds ratios indicated the FAST group was 5.5 times more likely to achieve a 10% weight loss at 18 months than the SLOW group (58.2 vs. 20.3%), and the MODERATE group was 2.5 times more likely than the SLOW group (38.5 vs. 20.3%). Within the context of lifestyle treatment, these results suggest that there were both short- and long-term advantages to a fast rate of initial weight loss and that those who lost weight quickly were not more susceptible to relapse. These findings suggest that a high rate of initial weight loss is associated with long-term success in weight management.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis: Thesis (M.S.)--University of Florida, 2008.
Local: Adviser: Perri, Michael G.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2010-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022023:00001


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THE IMPACT OF RATE OF INITIAL WEIG HT LOSS ON LONG-TERM SUCCESS IN THE TREATMENT OF OBESITY: DOES SLOW AND STEADY WIN THE RACE? By LISA MARIE NACKERS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2008 1

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2008 Lisa Marie Nackers 2

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To my parents, who are my inspiration 3

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ACKNOWLEDGMENTS I would like to thank my mentor, Dr. Mich ael Perri for his support, guidance, and wisdom. I would also like to thank the memb ers of my supervisory committee, Dr. Eileen Fennell, Dr. Michael Robinson, and Dr. Sheila Eyberg, for their time and assistance. Additionally, I would lik e to thank my colleagues in the TOURS lab for their constant encouragement and assistance on this project. Finally, I would especia lly like to thank my family for providing unwavering love and support and for encouraging me to continue striving toward my goals. 4

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TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................4 LIST OF TABLES................................................................................................................. ..........7 LIST OF FIGURES.........................................................................................................................8 ABSTRACT.....................................................................................................................................9 CHAPTER 1 INTRODUCTION................................................................................................................. .11 Obesity........................................................................................................................ ............12 Prevalence........................................................................................................................12 Obesity-Related Health Conditions.................................................................................12 Obesity-Related Economic Factors.................................................................................14 Behavioral Treatment for Obesity..........................................................................................14 Impact of Weight Change on Disease Risk............................................................................15 Diabetes....................................................................................................................... ....15 Hypertension....................................................................................................................16 Hyperlipidemia................................................................................................................17 Predictors of Long-Term Weight Loss Success.....................................................................18 Slow Initial Rate of Weight Loss....................................................................................18 Fast Initial Rate of Weight Loss......................................................................................19 Specific Aims and Hypotheses...............................................................................................20 2 MATERIALS AND METHODS...........................................................................................23 Research Methods and Procedures.........................................................................................23 Participants......................................................................................................................23 Procedure.........................................................................................................................24 The TOURS Intervention................................................................................................25 Measures..........................................................................................................................26 Statistical Analyses........................................................................................................... ......29 Weight-Change Categories..............................................................................................29 Primary Aims................................................................................................................... 29 Secondary Aims...............................................................................................................30 3 RESULTS...................................................................................................................... .........32 Weight-Loss Groups...............................................................................................................32 Characteristics by Weight-Loss Group...................................................................................32 Primary Aims................................................................................................................... .......33 5

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Initial Rate of Weight Loss and Weight Outcomes.........................................................33 Month 0 to Month 6.................................................................................................33 Month 6 to Month 18...............................................................................................33 Month 0 to Month 18...............................................................................................34 10% Weight Loss at Month 18........................................................................................34 Secondary Aims................................................................................................................. .....34 Initial Weight Loss, Attendance, Adherence and Weight Outcomes..............................34 Initial Rate of Weight Loss and Metabolic Risk Factors................................................35 Initial Rate of Weight Loss, Attendance, Adherence, Caloric Intake, and Physical Activity............................................................................................................................35 4 DISCUSSION................................................................................................................... ......42 Primary Aims................................................................................................................... .......42 Secondary Aims................................................................................................................. .....44 Attendance and Adherence..............................................................................................44 Metabolic Risk Factors....................................................................................................46 Limitations.................................................................................................................... ..........46 Clinical Implications.......................................................................................................... .....48 LIST OF REFERENCES...............................................................................................................50 BIOGRAPHICAL SKETCH.........................................................................................................58 6

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LIST OF TABLES Table page 2-1 Baseline demographic characteristics of the sample of 298 women .................................31 3-1 Baseline demographic characteristics of participants in FAST, MODERATE, and SLOW groups ....................................................................................................................37 3-2 Pretreatment caloric intake physical fitness, and metabolic risk factor levels for FAST, MODERATE, and SLOW groups ..........................................................................37 3-3 Behavioral correlates of weight loss ..................................................................................38 3-4 First month attendance and adherenc e rates for FAST, MODERATE, and SLOW groups .................................................................................................................................38 3-5 Week 4 average caloric intake a nd steps for FAST, MODERATE, and SLOW groups .................................................................................................................................38 7

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LIST OF FIGURES Figure page 3-1 Weight changes according to weight-loss group ...............................................................39 3-2 Percentage of weight-loss groups attaining a 10% reduction at Month 18 ........................40 3-3 Net changes in metabolic risk factors ................................................................................41 8

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Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THE IMPACT OF RATE OF INITIAL WEIG HT LOSS ON LONG-TERM SUCCESS IN THE TREATMENT OF OBESITY: DOES SLOW AND STEADY WIN THE RACE? By Lisa Marie Nackers May 2008 Chair: Michael G. Perri Major: Psychology Controversy exists regarding rate of initial weight loss and long-term success in weight management. Some theorists contend that a rapi d rate of initial loss may result in poorer longterm success and that a slow, gradual decrease may lead to better maintenance of lost weight and a superior long-term outcome. We examined this question in the context of a randomized trial of lifestyle treatment in which participants were enc ouraged to reduce their inta ke so as to achieve a weight loss of 0.45 to 0.91 kg/week (i.e. 1 to 2 lb /week). We classified participants based on their rate of weight lo ss during the first month of treatment as FAST ( > 0.68 kg/week [ > 1.5 lb/week], n = 55), MODERATE ( > 0.23 and < 0.68 kg/week [ > 0.5 and < 1.5 lb/week], n = 96) and SLOW (< 0.23 kg/week [< 0.5 lb/week], n = 79) losers. These groups were drawn from a sample of middle-aged (mean = 59.3 yr) obese women (mean BMI = 36.8) who participated in a six-month lifestyle intervention that was follo wed by one year of extended care. The three groups did not differ at baseline with respect to age, weight, BMI, fitne ss, nutritional intake, or physical activity patterns. The FAST, MODERA TE, and SLOW groups differed significantly from each other with regard to net mean wei ght change at six months (-13.9, -9.6, and -5.9 kg, respectively, ps < .001) and at 18 months (-11.5, -7.8, and -4.8 kg, respectively, ps < .05). No significant differences in weight regain betw een 6 and 18 months were found among groups (2.5, 9

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1.8, 1.1 kg, respectively). Odds ratios indicated the FAST group was 5.5 times more likely to achieve a 10% weight loss at 18 months th an the SLOW group (58.2% vs. 20.3%), and the MODERATE group was 2.5 times more likely than the SLOW group (38.5% vs. 20.3%). Within the context of lifestyle treatment, these results suggest that ther e were both shortand long-term advantages to a fast rate of initial weight loss and that those who lost weight quickly were not more susceptible to relapse. These fi ndings suggest that a high rate of initial weight loss is associated with long-term success in weight management. 10

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CHAPTER 1 INTRODUCTION Successful weight loss maintenance in obese in dividuals has been de fined as a reduction of 10% or greater of initial body weight maintained for at least one year (National Heart, Lung, and Blood Institute, 1998; Wing & Hill, 2001). Re search has demonstrated that lifestyle interventions consisting of 15 to 30 weekly group sessions result in an 8 to 10% reduction of initial body weight (Jeffery et al., 2000; Perri & Fuller, 1995 ; Wadden, Butryn, & Byrne, 2004); however, these beneficial losses are rarely maintained long-t erm (Perri, 1998; Wadden et al., 2004). Because weight regain has been shown to have an adverse impact on metabolic risk factors (Klein, 2001; Krebs et al., 2002; Moore et al., 2000), considerable efforts have been placed on identifying individual charact eristics or behavioral factors that may be associated with long-term success in weight loss maintenance (Elfhag & Rssner, 2005; Vogels, Diepvens, & Westerterp-Plantenga, 2005; Wadden et al., 1992). St udies have shown that ra te of initial weight loss, even within the first few weeks of treatme nt, may serve as a predictor of long-term success (Carels, Cacciapaglia, Douglass, Rydin, & OBrien, 2003; Fogelholm, Kukkonen-Harjula, & Oja, 1999; Jeffery, Wing, & Ma yer, 1998; Sbrocco, Nedegaard, Stone, & Lewis, 1999; Wadden et al., 1992), but controversy exists regarding the ideal initial rate of loss (Jeffery et al., 1998; Sbrocco et al., 1999; Wadden et al., 1992). Losing weight at a slow, yet steady initial rate has been shown to result in continued weight loss, reduced risk for weight regain, and successful long-term weight loss maintenance (Sbrocco et al., 1999). Conversel y, losing weight at a high initial rate has also been found to produce long-term success (Astrup & Rssner, 2000; Carels et al., 2003; Fogelholm et al., 1999; Jeffery et al., 1998), and degree of weight loss within the first month of intervention has been labeled as the best predictor of weight loss at post-treatment follow-up (Wadden et al., 1992). 11

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While losing weight at a more rapid initial rate has been coupled with greater long-term weight loss, it is also associated with a greater amount of regain (Jeffe ry et al., 1998; Wadden, Foster, & Letizia, 1994). This finding suggests that a larger initial weight loss may actually serve as a risk factor for later weight regain (McGuire, Wing, Klem, Lang, & Hill, 1999; Weiss, Galuska, Kettel Khan, Gillespie, & Serdula, 2007; Wing & Hill, 2001). At present, controversy exists on how the degree of short-term weight loss affects longterm success. Thus, the current study examined the impact of rate of initial weight loss on long-term maintenance of lost weight. Obesity Prevalence Over the past four decades, the prevalence of obesity (defined as a Body Mass Index, BMI, > 30 kg/m 2 ) in the United States has increased markedly. Reports from the National Health and Nutrition Examination Survey (NHANES) illustrate that rates of obesity in adults rose from 12.8% in 1960-1962 (Flegal, Carro ll, Kuczmarski, & Johnson, 1998) to 32.2% in 2003-2004 (Ogden et al., 2006). Trends suggest that by 2015, 41% of adults in the United States will be classified as obese (Wang & Beydoun, 2007) Certain sub-groups of the population are disproportionately affected, with those from low socio-economic status and inhabitants of rural areas exhibiting higher rates of obesity (Cha ng & Lauderdale, 2005; Flegal, Carroll, Ogden, & Johnson, 2002; Hedley et al., 2004; Patterson, Moore, Probst, & Shinogle, 2004). Similarly, higher rates are observed in olde r versus younger adults and in wo men versus men (Ogden et al., 2006). Obesity-Related Health Conditions The increasing prevalence of obesity has been directly linked with increased morbidity. Obesity is associated with increased risk cardiovascular for disease (Flegal, Graubard, Williamson, & Gail, 2007; Gregg et al., 2005; W ilson, DAgostino, Sullivan, Parise, & Kannel, 12

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2002), hypertension (Mokdad et al ., 2003), hypercholesterolemia (Bro wn et al., 2000; Mokdad et al., 2003), type 2 diabetes (Flega l et al., 2007; Mokdad et al., 2003) asthma, arthritis (Mokdad et al., 2003), gallbladder disease (Field et al., 2001 ), sleep apnea (Vgontzas et al., 1994), renal disease (Flegal et al., 2007), and breast, pancreatic, and prostate cancers (Dumitrescu & Cotalra, 2005; Field et al., 2001; Freedla nd & Aronson, 2005). Obese indivi duals are also 2.75 times more likely to experience functional impairmen t (e.g. walking or lifting) than their normal weight counterparts (Alley & Chang, 2007). Ba sed on the Medical Expenditure Panel Survey, it has been estimated that obese men and women in the United States lose 912,000 and 1.95 million health-related quality of life years, respectiv ely, compared to those with a healthy BMI (Muennig, Lubetkin, Jia, & Franks, 2006). Obesity is also related to an increased mort ality and decreased life expectancy. Estimates of excess deaths per year at tributable to obesity range from 111,909 (Flegal, Graubard, Williamson, & Gail, 2005) to as high as 414,000 (Mokdad, Marks, Stroup, & Gerberding, 2004). Additionally, results from the Framingham Heart Study suggest that BMI at ages 30 to 49 predicts mortality in future decades, with five to seven years of life lost in obese individuals (Peeters et al., 2003). Epidemiological estimates suggest that obesity le ads to a reduction in quality-adjusted life expectancy by 4.4 to 7.2 ye ars, indicating obese in dividuals will live fewer healthy, disease-free years th an those of normal weight (Muennig et al., 2006). In addition to adverse physical outcomes, obesity is also associated with negative psychosocial consequences. Recent studies have linked obesity to stigmatization in employment, education, and healthcare (Puhl & Brownell, 2001) and have found that close relationship partners (i.e. friends, parents, and spouses) serve as the worst sources of stigmatization (Puhl, Moss-Racusin, Schwartz, & Brownell, in press). Obese individuals experience lower quality of 13

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life and higher levels of de pression (Fontaine & Barofsky, 2001; Jia & Lubetkin, 2005; Wadden, Womble, Stunkard, & Anderson, 2002). Obese women are also at in creased risk for suicidality (Carpenter, Hasin, Allison, & Faith, 2000). Obesity-Related Economic Factors The hazardous health consequences of obes ity are accompanied by a significant financial burden. In the United States, 9.1% of healthca re expenditures are attributed to obesity, accounting for 78.5 billion dollars per year, a cost that rivals that associated with smoking (Finkelstein, Fiebelkorn, & Wang, 2003). These costs increase with both age and degree of obesity (Arterburn, Maciejewski, & Tsevat, 2005; Wee et al., 2005). In the year 2000, medical expenditures for the 5% of the population who were morbidly obese (BMI > 40) surpassed 11 billion dollars, a cost that was 81% greater th an health care costs for normal weight adults (Arterburn et al., 2005). It ha s been estimated that a sustained modest weight loss of 10% body weight would reduce expected lif etime medical care costs of di seases associated with excess weight by $2,200 to $5,300 per person (Oster, Thompson, Edelsberg, Bird, & Colditz, 1999). Behavioral Treatment for Obesity With the increased prevalence and adverse out comes associated with obesity comes an increased need for effective weight-loss treatments Lifestyle, or behavi oral, treatment programs utilize cognitive-behavioral st rategies to modify eating and activity patterns to produce a negative energy balance necessary to lose weight (Wadden, Crerand, & Brock, 2005). This intervention applies classical learning theory to weight loss by identifying and modifying the antecedents and consequences that are associat ed with unhealthy eating patterns and low levels of physical activity and by alteri ng the environment to increase a nd develop habits that promote healthy behaviors (Stuart, 1967; Wadden et al., 2005; Wing, 2002). Behavioral treatment utilizes self-monitoring through the use of daily food and physical activity records, calorie and activity 14

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goal setting (e.g., a deficit of 500-10 00 kcal/day combined with 30 min/day of physical activity), performance feedback and problem solving, reinforcement, stimulus control, and cognitive restructuring to achieve these goa ls (Wadden & Foster, 1992). Reviews of randomized trials show that comprehensive behavioral modification programs, which typically include weekly group treat ment sessions for four to six months, result in an 8% to 10% reduction of initial body weight, or an averag e loss of 0.5 kg (roughly 1 lb) per week (Jeffery et al., 2000; Perri & Fuller, 1995; Wadden, Butryn, & Byrn e, 2004; Wadden et al., 2005). Weight losses of this magnitude have been associated with reducti ons in adverse health conditions and risk factors associated with obe sity (National Heart, Lung, and Blood Institute, 1998). Unfortunately, long-term follow-up evalua tions indicate that traditional behavioral treatment induced weight losses are not well ma intained (Perri, 1998; Wadden et al., 2004). A recent review by Wadden et al. ( 2004) indicated that in the year following 20 to 30 weeks of group lifestyle modification treatment, patients regain 30% to 35% of their lost weight. After the first year, this weight regain slows, but 18 months following program entry, only about 50% of the initial lost weight is mainta ined (Jeffery et al., 2000). Five years after treatment, 50% or more of patients return to their initial body weight (Wadden, Sternberg, Letizia, Stunkard, & Foster, 1989). Another review found that only 13% to 22% of patients who initially lost > 5 kg maintained this weight loss at five year follow-up (Wing & Hill, 2001). Thus, the pattern associated with behavioral treatment entails succ essful initial weight loss followed by a reliable regain of lost weight (Jeffery et al., 2000). Impact of Weight Chan ge on Disease Risk Diabetes Considerable evidence supports the notion that mode st weight loss results in substantial improvements in glycemic control, thus reducing the risk for type 2 diabetes. The Diabetes 15

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Prevention Program (DPP), a randomized clinical trial that involved 3200 obese individuals at high risk for developing type 2 diabetes, found that men and women receiving lifestyle intervention for weight loss expe rienced a 58% reduced risk of developing type 2 diabetes (Diabetes Prevention Program Research Group, 2002). Further analyses indicated that for every kilogram of weight lost, ther e was a 16% reduction in diabetes risk (Hamman et al., 2006). Similarly, the Finnish Diabetes Prevention Study, which randomized 522 middle-aged overweight participants with impair ed glucose tolerance to either lifestyle intervention or control group, found that the intervention group lost an average 4.7% of initial body weight and experienced a 58% reduced risk of diabetes compared to the control group (Tuomilehto et al., 2001). A recent meta-analysis of nine randomized trials found a relative risk for one-year incidence of type 2 diabetes of 0.55 for particip ants receiving lifestyle intervention for weight loss compared to those in control groups (Yam aoka & Tango, 2005). Epidemiological estimates have calculated that a sustained modest weight loss would reduce the expect ed years of life with type 2 diabetes by 0.5 to 1.7 (Oster et al., 1999). Weight regain has an adverse impact glycemic control. While participants in the DPP regained roughly one-third of thei r lost weight and stil l experienced reductions in diabetes risk (Diabetes Prevention Research Group, 2002), other reports indicate that t hose who regain lost weight experience no improvement in diabetes risk (Moore et al., 2000) or only experience improvement if net weight loss remain s above 5% (Krebs et al., 2002). Hypertension Lifestyle interventions focused on achieving mode st weight losses of 5% to 10% of initial body weight, even without dietary sodium reduc tion, have proven effective in reducing hypertension and the need for pharmacologic inte rvention regardless if th e participant remains 16

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obese (Mertens & Van Gall, 2000; Whelton et al., 1998). The Trials of Hypertension Prevention (TOHP) project, consisting of a th ree-year weight-loss interventi on, showed that participants who lost approximately 5% of th eir initial body weight at six mont hs and maintained this weight loss for 30 months experienced a relative risk for hypertension of 0.35 compared to those who did not achieve this weight loss (Stevens et al ., 2001). A meta-analysis of 25 randomized trials suggested that blood pressure is reduced by 1.05 mm Hg (systolic) and 0. 92 mm Hg (diastolic) per kilogram of weight loss (N eter, Stam, Kok, Grobbee, & Geleijn se, 2003). Expected years of life with hypertension would be reduced by an estimated 1.2 to 2.9 with successful weight loss (Oster et al., 1999). Conversel y, results of the TOHP project demonstrate that much or full weight regain leads to a stea dy increase to baseline levels of blood pressure at 36 months (Stevens et al., 2001). Hyperlipidemia Weight loss has also been associated with a clinically significant reduction in lipid profile. Dattilo and Kris-Ethertons meta-ana lysis of 70 articles (1992) found that for each kilogram of weight lost, total cholesterol was reduced by 0.91 mg/dL, LDL cholesterol by 0.36 mg/dL, and triglycerides by 0.27 mg/dL. Similarly, it is expected that a weight loss of 4.5 kg (10 lbs) can reduce LDL cholesterol by 5% to 8% (Fle tcher et al., 2005). Epidemiological estimates suggest that a modest weight loss woul d reduce the expected years of life with hypercholesterolemia by 0.3 to 0.8 (Oster et al., 1 999). Degree of maintained weight loss may be a determinant of reduction in lipid profile bene fits. Wadden, Anderson, and Foster (1999) found that a 5% sustained weight loss was necessary for decreases in triglyceride concentrations to remain significant, and a 10% maintained weight loss was necessary for LDL cholesterol to remain lowered. 17

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Predictors of Long-Term Weight Loss Success Over two decades ago, Brownell (1984) noted th e usefulness of identif ying predictors of success so that weight-loss programs could be tailored to those who are most likely to succeed. A recent meta-analysis by Teixeira, Going, Sardinha, and Lohman (2005) found, among a large number of baseline characteristic s studied, only less previous diet ing, fewer previous weight loss attempts, self-motivation, general efficacy, and autonomy held consistent evidence as predictors of successful weight-loss. Research has show n that, during weight management programs, both higher rates of attendance (C arels et al., 2003; Wadden et al., 1992) and higher rates of adherence, as measured by self-monitoring a nd recording daily dietary intake (Baker & Kirschenbaum, 1993; Boutelle & Kirschenbaum 1998), have been correlated with long-term weight loss success. Studies have also indicated that rate of weight loss within the first few weeks of behavioral treatment may also serve as a predictor of long-term success (Carels et al., 2003; Fogelholm et al., 1999; Jeffery et al., 199 8; Sbrocco et al., 1999; Wadden et al., 1992). Slow Initial Rate of Weight Loss Some theorists contend that losing weight at a slow initial rate may lead to superior longterm loss and lower risk for weight regain. Beca use it is often difficult to maintain the degree of caloric restriction promoted by traditional beha vioral treatment programs for a prolonged period of time (Schlundt, Sbrocco, & Bell, 1989), Sbro cco and colleagues (Sbrocco et al., 1999) developed an alternate intervention called b ehavioral choice treatment. Based upon a decision-making model (Sbrocco & Schlundt, 1998), behavioral choice treatment teaches participants to use mild caloric restriction, reducing caloric intake from an estimated 2500 kcal/day to 1800 kcal/day, and to make healt hy decisions regarding eating choices without considering their eating pa tterns as dieting. Weight loss is therefore expected to be slower 18

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initially, but continuous as part icipants maintain new decision making regarding healthy eating patterns. Sbrocco et al. (1999) conducted a 13-week randomized trial in which groups of obese women took part in either a trad itional behavioral treatment that encouraged significant caloric reduction so as to achieve a substantial initial wei ght loss, or a behavioral choice treatment that promoted mild caloric rest riction and a slow, yet steady weight lo ss. Results indicate that at both mid-treatment and post-treatment, those in th e traditional behavioral treatment achieved significantly greater weight losse s; however, at three-month follow-up, this difference was no longer apparent. The behavioral choice treatmen t group continued to lose weight and achieved significantly greater weight losses at both 6and 12-mont h follow-up (-7.0 and -10.1 kg, respectively) than the traditional behavioral treatment group, which experienced continued weight regain from 6 to 12 months (-4.5 and -4.3 kg, respectively). T hus, a slow and steady initial weight loss may produce larger long-term we ight loss that is not susceptible to regain, leading to successful weight loss maintenance. Fast Initial Rate of Weight Loss Other researchers purport that weight loss o ccurring at a high initial rate leads to better long-term outcomes. Recent reviews of weight lo ss patterns have concluded that the greater the initial weight loss in obese patients, the larger the total weight loss retention at long-term followup (Astrup & Rssner, 2000; Elfhag & Rssner, 2005) Fogelholm et al. (1999) conducted a 12week weight reduction program followed by a 40-week maintenance period and found that weight loss during the initial 12-week treatment served as the strongest positive predictor of further weight change during the subsequent period. Similar pred ictive results have been shown when assessing weight loss within the initial six weeks (Carels et al., 2003) and within the first month of traditional behavioral treatment program s (Wadden et al., 1992). Jeffery et al. (1998) 19

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conducted a randomized trial in which 130 men and women participated in an 18-month weightloss treatment program with an additional 12month follow-up. Participants were then categorized into tertiles according to the maximum amount of weight loss. Those participants in the highest maximum weight-loss cate gory lost weight at more than twice the initial rate of those in the lowest tertile. The results indicated that 23% of those partic ipants who achieved the highest initial weight lo ss (i.e. highest tertile of maximu m weight loss [average loss of 0.68 kg/week]) attained a clinically significant 10% reducti on in body weight at 30 months compared to only 9% of those who lost a moderate initia l amount (i.e. middle tertile [average loss of 0.58 kg/week]) and 2% who lost the l east initially (i.e. lowest tertil e [average loss of 0.29 kg/week]). However, the results also demonstrated that t hose who had the largest in itial losses experienced larger and more rapid weight rega in than those who initially had smaller losses. Similar findings have documented that a larg e initial weight loss is a risk factor for weight regain (McGuire et al., 1999; Sbrocco et al., 1999; Wadden, Foster, & Le tizia, 1994; Weiss et al., 2007; Wing & Hill, 2001). In sum, many behavioral treatment progr ams have proven effective in promoting clinically significant weight lo sses, but long-term weight reduc tion is difficult to maintain. Therefore, predictors of success in weight-loss programs have been examined. There is evidence to suggest that initial ra te of weight loss, asse ssed in as few as four weeks of treatment, is associated with both greater long-term success and higher rates of weight regain. Thus, it remains unclear whether there exists an optimal in itial rate of weight loss for effective long-term weight management. Specific Aims and Hypotheses The present study examined the effects of rate of weight loss within the first month of a six-month lifestyle intervention on long-term (18month) weight reduction in a group of women 20

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ages 50-75 years. Women who lost weight at a SLOW rate (< 0.23 kg/ week [< 0.5 lb/week]) were compared to women who achieved MODERATE ( > 0.23 to < 0.68 kg/week [ > 0.5 to <1.5 lb/week]) and FAST ( > 0.68 kg/week [ > 1.5 lb/week]) rates of weight loss within the first month of intervention. The first aim of this study was to determine if a SL OW rate of initial weight loss was better associated with weight loss at 6 and 18 months and le ss weight regain from 6 to 18 months than a MODERATE or FAST rate of loss We tested the hypothesis that those women who lost at a SLOW rate would experience greater shortand l ong-term weight losses and lesser weight regain. In conjunction with the defini tion of successful weight loss maintenance, the second aim of the present study was to assess if a SLOW rate of initial weight loss was associated with a greater likelihood of achievi ng a 10% weight reduction at 18 months than a MODERATE or FAST rate of loss. We tested the hypothesis that women who lost at a SLOW initial rate would be more likely to achieve a 10% weight loss at 18 months. A secondary aim of this study was to evaluate if overall rate of we ight loss at one month was associated with weight reductions at both 6 and 18 months and weight regain from 6 to 18 months. We expected that weight loss at one month would be related to weight loss at both 6 and 18 months as well as weight regain between these two time points. Additionally, we sought to determine if rate of attendance and rate of adherence, as assessed by the number of program sessions attended and self-monitoring daily diet ary records completed, respectively, during the first month of treatment were associated with weight loss at 1, 6, and 18 months, as well as with weight regain from 6 to 18 months. We hypothesi zed that both rate of attendance and rate of adherence within the first month of lifestyle trea tment would be related to greater weight loss at 1, 6, and 18 months, but not with weight regain from 6 to 18 months. A final exploratory aim was to examine the rate of in itial weight loss on both shortand long-term changes in blood 21

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pressure (systolic), lipid profile (LDL-choleste rol and triglycerides), and glycemic control (HbA1c). 22

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CHAPTER 2 MATERIALS AND METHODS Research Methods and Procedures The present study was a secondary analysis th at utilized data co llected in the TOURS (Treatment of Obesity in Underserved Rural Settings) project. TOURS was a randomized controlled weight-loss trial of behavioral interventions in six medically underserved rural counties in Northern Flor ida (Perri et al., 2005). Participants Participants were 298 obese women be tween the ages of 50 to 75 years ( M = 59.3, SD = 6.2 years) with a mean baseline weight of 96.5 kg ( SD = 14.9 kg) and Body Mass Index (BMI) of 36.8 kg/m 2 ( SD = 5.0 kg/m 2 ). The majority of participants classified themselves as Caucasian (75.5%) followed by African American, (20.5%), Other (2.3%), and Hispanic/Latino (1.7%). The sample was well-educated, with 53.7% attendi ng some college or receiving a college degree, and 9.7% achieving a postgraduate degree; th e remaining 36.6% reported completing less than 12 years of education. Additional baseline dem ographic characteristics can be found in Table 21. No upper limit was placed on BMI; however, th e use of a standard balance beam scale required exclusion of women w ho weighed greater than 159 kg (350 lbs). Women were also excluded if they lost an excess of 4.5 kg (10 lb s) within the preceding six months. Additional exclusion criteria include cancer within the previous five years (except non-melanoma skin cancer), serious infectious dis ease, myocardial infarction, cereb rovascular accident or unstable angina within the past six months, congestive he art failure, chronic hepatitis, cirrhosis, chronic malabsorption syndrome, chronic pancreatitis, irritable bowel syndrome, previous bariatric surgery, history of solid organ tr ansplantation, history of musculo-skeletal conditions that limit 23

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walking, chronic lung diseases limiting physical activity, serum creatinin >1.5 mg/dL, anemia (hemoglobin <10 g/dL), or any additional condition likely to limit five-year life expectancy or interfere with lifestyle intervention. Diabetic women receiving active treatment were included with the approval of their primary provider, but women whose fasti ng blood glucose was >125 mg/dL at screening were not allowed to particip ate if they were not known to have diabetes. Regardless of medication treatm ent, women with fasting serum triglycerides >400 mg/dL and resting blood pressure >140/90 mm Hg at screening were excluded. Use of antipsychotic agents, monoamine oxidase inhibitors, systemic cortic osteroids, human immunodeficiency virus or tuberculosis antibiotics, chemotherapeutic drugs, or weight-loss drugs al so was exclusionary. Women who indicated a major psychiatric disorder or exces sive alcohol intake, and those who were unwilling or unable to provide informed cons ent, unable to read English at a fifth grade level, participating in another randomized re search project, or unwilling to accept random assignment were also not allowed to enroll. Procedure Participants in the TOURS study were re cruited through direct mailings, newspaper announcements, and presentations at community cen ters and events. Telephone screenings were conducted with prospective participants, and thos e that passed the initial eligibility screening were scheduled for an in-person baseline visit. At this visit, eligible women received a detailed explanation of the study and provided their informed consent. Additionally, participants completed questionnaires on demographic info rmation, medical histor y, current medication inventory, dietary intake, physical activity, health-related quali ty of life, depressive symptoms, and problem-solving skills. Assessments of height, weight, and abdominal girth as well as resting heart rate, blood pressure and blood-draw for serum analys is were taken. To determine functional mobility, the 6 Minute Walk Test (6MW T) was administered. Within two weeks of 24

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the first group session, participants completed a prestart visit to ensure we ight stability prior to treatment and to repeat the 6MWT. Only the results from the second walk test were used to reduce the potential impact of practice. An additional blood-draw was conducted on those women who had gained or lost greater than 4.5 kg to ensure their metabolic profile had not changed from baseline. All measures were repeat ed after six months of the intervention and at study conclusion after a total of 18 months. The TOURS Intervention The TOURS lifestyle modification interven tion consisted of two phases. Phase I included 24 weekly group intervention sessions (10 to 15 participants per group) held at Cooperative Extension Offices in si x rural counties in Northern Flor ida. Each session lasted 90 minutes and was designed to decrease caloric intake and increase moderate intensity physical activity to facilitate a weight loss of approximately 0.4 kg/week. Dietary goals involved reducing energy intake by 500 to 1000 kcal per day, maintaining a balanced diet consisting of 25% to 30% total kcal from fat, 15% from protein, and the remaining 60 to 65% from carbohydrates. Participants were al so encouraged to increase fruit and vegetable consumption to five servings per day and whole grains to three or more servings per day. Physical activity goals focused on attaining 180 minutes of moderate intensity exercise per week, or 30 minutes per day for six days per week. Pedometers were supplie d and participants were encouraged to add 3000 or more steps per day above baseline levels. Pa rticipants were also instructed to maintain detailed daily written records of thei r dietary intake and physical activity. Phase I also included cognitive and behavior al skills training for weight loss that consisted of self-monitoring, goal-setting, self -reinforcement, stimulus control, cognitive restructuring, and increasing social support. Weekly sessions include d a private weigh-in, a review of participants progre ss toward goals, a discussion of nutrition and exercise, feedback 25

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and encouragement from group leaders and other group members, and skills training related to the behavioral strategies for weight loss. Because these interventions were conducted in rural counties, they were also tailored to special issues of rural southern women and incl uded cooking demonstrations every other session to illustrate low-fat, low-calorie food prepar ation, with special focu s on Southern Cooking. Additionally, sessions incl uded stress and depression coping stra tegies and techniques for eating away from home. The specific dietary objectives of the TOURS intervention were derived from the Therapeutic Lifestyle Changes recommended in the Adult Treatment Panel III Report of the National Cholesterol Education Program (2001). The physical activity goals and methods are based on recommendations of the Surgeon General (US Department of Health and Human Services, 1996) and the American Co llege of Sports Medicine (2001). Phase II consisted of an extended care 12-m onth follow-up program in which participants were encouraged to maintain the new eating an d exercise habits learned during the Phase I intervention. Participants were encouraged to continue monitoring diet ary intake and physical activity through the use of record logs. At the beginning of Phase II, par ticipants were randomized to one of three extended-care progr ams: an office-based (in-person) maintenance program, a telephone-based maintenance program, or an educational (mail) control condition. All participants received cont act twice per month in the fo rm of group sessions, telephone contact, or biweekly newsletters, respectively. Measures Body weight. Weight was measured to the nearest 0.1 kilogram using a certified balance beam scale. Participants were weighed at weekly group sessions and at assessments at Month 0, 6, and 18 while wearing light indoor clothing, without shoes, and with empty pockets. Weight 26

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change scores were calculated by subtracting partic ipants weight at 6 and 18 months from Month 0 and by subtracting weight at 18 months from six months. Blood pressure. A Registered Nurse (RN) obtained pa rticipants resting systolic and diastolic blood pressure using a standardized protocol (Choba nian et al., 2003). Three blood pressure readings, spaced one minute apart, were taken, and the last two r eadings were averaged for the analysis. If a large discrepancy was observed between the last two readings, an additional reading was taken and the median for the final three readings was used. For the present study, only systolic blood pressure was examined because of its relation to cardiovascular disease risk (Prospective Studies Collaboration, 2002; Vasan et al., 2001). It ha s been estimated that a three mm Hg reduction in systolic blood pr essure leads to reductions of 8% in stroke mortality and 5% in coronary heart disease mortality (Stamler, 1991). Blood analyses: LDL-cholesterol, triglycerides, HbA1c. The study RN drew blood samples, which were sent to Quest Diagnostics Clinical Laboratories for metabolic and lipid profile analysis. From the metabolic profile, He moglobin A1c (HbA1c), which is a more durable measure than fasting glucose (Centers for Dis ease Control and Prevention, 2001), was used to measure glycemic control. Glycemic control has been highly related to di abetes risk (American Diabetes Association, 2001). From the lipid pr ofile, LDL-cholesterol an d triglycerides were used to assess cardiovascular disease risk. Triglycerides and LDL-cholesterol each constitutes independent components of overall lipid contro l (Tanne, Koren-Morag, Graff, & Goldbourt, 2001), and each contributes inde pendently to cardiovascular risk (National Cholesterol Education Program, 2001). Lowering LDL-choleste rol and triglycerides can significantly reduce the risk of stroke, coronary events, coronary artery procedures, and mortality (National Cholesterol Education Program, 2001). 27

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Caloric intake. The Block 95 Food Frequency Questi onnaire, a revised version of a previously validated survey (Block et al., 1986), asks respondents to es timate consumption of a wide variety of foods. Scoring yields estimat es of daily caloric intake, macroand micronutrient intake and intake by specific food groups (e.g. fruits, vegetables, grains, etc.). The Block has been strongly correla ted with four-day food records (Subar et al., 2001). Estimated daily caloric intake was taken for Month 0. Calo ric intake within the first month was assessed according to daily written food reco rds kept by each participant. Physical fitness. Participants completed t he 6 Minute Walk Test (6MWT), a performance-based measure of physical fitness used in populations with low exercise capacity (e.g., elderly persons, those with functional limitati ons) and for whom rigorous fitness tests like treadmill exercise tests would be inappropriate (Peeters & Mets, 1996). Participants walked for six minutes along a clearly marked indoor course and were asked to cover as much ground as possible. Distance walked was measured to th e nearest foot. The 6MWT was completed twice during a screening visit, and t he first results were discarded due to known practice effects. The 6MWT has been shown to be highly reliable in populations with low exercise capacity (Kervio, Carre, & Ville, 2003) and to have convergent vali dity, as suggested by a strong correlation with peak oxygen uptake during maxi mal exercise testing ( r = .68; Zugck et al., 2000). Physical fitness within the first month of treatment was assessed according to the number of steps recorded by participants on pedometers. Attendance. Session attendance was recorded if the participant arrived at the treatment session and was weighed by a staff member. Adherence. Because self-monitoring of dietary inta ke and physical activity has been considered a critical aspect of behavioral treatment programs (Baker & Kirschenbaum, 1993; 28

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Boutelle & Kirschenbaum, 1998; Brownell, 2000; Wing, 1998), participants were asked to complete food and activity record s daily throughout Phase I and at least three times per week during Phase II of the study. The total number of food records maintained serves as a better predictor of successful weight loss than actual content (Streit, Stevens, Stevens, & Rssner, 1991). For the present study, the to tal number of daily records comp leted was used as a measure of adherence to the intervention. Because participants did not re turn food diaries during the first week of the treatment program, adherence was calculated according to the number of food records kept between weeks two and four. Statistical Analyses Weight-Change Categories Participants were classified according to their rate of weight loss dur ing the first month of the intervention. Change scores were calculated by subtractin g Month 1 weight values from Month 0 values. These numbers we re then divided by four to achie ve an average weekly rate of weight loss. Participants were then categorized as FAST ( > 0.68 kg/week [ > 1.5 lb/week]), MODERATE ( > 0.23 and < 0.68 kg/week [ > 0.5 and < 1.5 lb/week]) and SLOW (< 0.23 kg/week [< 0.5 lb/week]) weight losers. Only th ose women (n = 230) that had values at Month 0, 1, 6, and 18 were included in the present study. Primary Aims Weight change scores (kg) we re calculated to es tablish both short-term (Month 6 values Month 0 values) and long-term weight reduction (Month 18 values Month 0 values) and weight regain (Month 18 values Month 6 values). To determine if a SLOW rate of initial weight loss is better associated with weight loss than a MODERATE or FAST rate, we conducted one-way ANOVAs utilizing the aforementioned weight change scores as outcome variables. Family-wise 29

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error was constrained to = .05, r was calculated to measure effect size of associations, and Bonferroni corrections were applied to control the risk of type I error. To assess whether those in the SLOW gr oup were more likely than the MODERATE or FAST groups to achieve a 10% weight reduction at 18 months, percent change scores were calculated ([Month 18 values Month 0 values]/ Month 0 values 100), and Pearsons chisquare tests were conducted. Cramers V was utilized to determine strength of associations. Family-wise error was once again constrained to = .05. Odds ratios were also calculated to measure effect size of associations. Secondary Aims To evaluate our secondary aims of whet her overall weight loss, attendance, and adherence at one month of treatme nt were associated with weight change scores both shortand long-term, Pearsons correlation an alyses were conducted utilizing = .05. Change scores were calculated as defined above usi ng values at Months 0, 6, and 18 for systolic blood pressure (mm Hg), LDL-cholesterol (mg/dL), triglycerides (mg/dL), and HbA1c (%). One-way ANOVAs were conducted to examine whether those in th e SLOW group attained greater reductions in metabolic risk factors at 6 and 18 months. Family-wise error was again constrained to = .05, r was calculated to measure effect size of associatio ns, and Bonferroni correc tions were applied to control the risk of type I error. All statistical analyses were conducted us ing SPSS statistical so ftware (version 15.0). 30

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Table 2-1. Baseline demographic charac teristics of the sample of 298 women M SD Age (years) 59.3 6.2 Weight (kg) 96.5 14.9 BMI (kg/m) 36.8 5.0 n % Race/ethnicity (%) Caucasian 225 75.5 African American 61 20.5 Hispanic American 5 1.7 Other 7 2.3 Education < 12 years 109 36.6 Some college/college degree 160 53.7 Post-college 29 9.7 Total income < $20,000 66 22.1 $20,000,999 73 24.5 $35,000,999 62 20.8 $50,000,999 57 19.1 $75,000,999 24 8.1 > $99,999 10 3.4 Do not know/Did not report 6 2.0 31

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CHAPTER 3 RESULTS Weight-Loss Groups Of the original 298 TOURS participants, 36 we re excluded because they did not have a recorded weight at one month. Additionally, one participant had no recorded weight at six months and 31 did not have recorded weights at 18 months and thus were excluded from the present study. Therefore, the sample was composed of 230 obese women and categorized according to amount of weight loss at Month 1. The average weekly weight loss for the FAST, MODERATE, and SLOW group were -1.0, -0.5, and -0.0 kg, respectively. Characteristics by Weight-Loss Group Women in the FAST group (n = 55) were more likely to be Caucasian than those in the MODERATE group (n = 96; 2 (1) = 7.6, p < .01, Cramers V = 0.27) and SLOW group (n = 79; 2 (1) = 17.2, p < .001, Cramers V = 0.37). No additional baseline demographic differences were found among groups on age, BMI, weight, or education (Table 3-1). As assessed by the Block 95 Food Frequency questionnaire and the 6MWT, the weight-loss groups did not differ on baseline measurements of caloric intake and physica l fitness. Participants in each group also did not vary on any metabolic risk factor at pre-treat ment. Pre-treatment leve ls for each weight-loss group can be seen in Table 3-2. At the conclusion of six-month behavioral treatment, women were randomized to a Phase II follow-up pr ogram involving in-person, telephone, or mail contacts. No significant diffe rences in Phase II assignment were found among weight-loss groups, 2 (4) = 2.1, p = .71, Cramers V = 0.07. 32

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Primary Aims Initial Rate of Weight Loss and Weight Outcomes Weight outcomes (means and standard errors ) for all groups at Month 0, 6, and 18 are illustrated in Figure 3-1. Month 0 to Month 6 Of the variables examined in the study, race/ethnici ty and attendance rate within the first month of behavioral treatment were found to be related to net change in weight at Month 6 ( ps < .05), thus an ANCOVA was conducte d to assess group differences. At the conclusion of active treatment, the FAST, MODERATE, and SLOW gr oups differed significantly from each other with regard to net mean weight chan ges (-13.9, -9.6, and -5.9 kg, respectively; F (2, 225) = 33.91, p < .001, r = 0.45). Bonferroni-corrected comparisons showed that women in the SLOW group lost significantly less weight than th ose in the FAST and MODERATE groups ( ps < .001). An additional retrospective ANCOVA was conduc ted to assess if group differences in net mean weight change at six months remained when only the Caucasian participants (n = 178) were analyzed. Attendance rate within the firs t month was once again found to be a covariate ( p < .01). Results indicate that the FAST, M ODERATE, and SLOW group differences in net change in weight at six months remained signi ficant when the sample was limited to Caucasians ( F (2, 174) = 20.98, p < .001, r = 0.43). Bonferroni-corrected comparisons indicate that Caucasian women in the FAST and MODERATE gr oups lost significantly more weight at six months than Caucasian women in the SLOW group ( p < .001 and p < .05, respectively) Month 6 to Month 18 From conclusion of behavioral treatment to 18-month follow-up, amount of weight regain was assessed among groups. Results of a one-way ANOVA indicate the FAST, MODERATE, 33

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and SLOW groups did not significantly differ in net weight regain (2.5, 1.8, and 1.1 kg, respectively; F (2,227) = 0.77, p = .46, r = 0.08). Month 0 to Month 18 With regards to change in weight from pr e-treatment to 18-month follow-up, results of a one-way ANOVA show significant differences existed among FAST, MODERATE, and SLOW weight loss groups (-11.5, 7.8, and -4.8 kg, respectively; F (2, 227) = 11.05, p < .001, r = 0.30). Bonferroni-corrected comparisons indicated that women in the SLOW group lost significantly less weight overall than those in the FAST ( p < .001) and MODERATE ( p < .05) groups. 10% Weight Loss at Month 18 As successful weight loss main tenance is often defined as > 10% reduction in body weight maintained for at least one year, a chisquare analysis was c onducted to assess whether the SLOW group was superior at atta ining this goal at 18-months. Results (Figure 3-2) indicate that the FAST group was more likely to achieve a 10% body weight reduc tion at Month 18 than was the SLOW group (58.2% vs. 20.3%, respectively; 2 (1) = 20.29, p < .001, Cramers V = 0.39). Similarly, the MODERATE gr oup was superior in reaching th is goal when compared to the SLOW group (38.5% vs. 20.3%, respectively; 2 (1) = 6.87, p < .01, Cramers V = 0.20). Odds ratios indicate that those who, within the first month of behavi oral treatment, lost weight at a FAST rate were 5.5 times more likely to ac hieve successful weight loss maintenance at 18months than those who lost at a SLOW rate. Those who were categorized as MODERATE were 2.5 times more likely to attain a 10% reducti on at 18-months than those in the SLOW group. Secondary Aims Initial Weight Loss, Attendance, Adherence and Weight Outcomes Results of Pearsons correlation analysis indicate that initia l weight loss occurring within the first month of the behavioral treatment pr ogram proved to be significantly related to net 34

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weight change at both 6 and 18 months (ps < .001). No correlation was found between initial change in weight during Month 1 and weight re gain between Months 6 and 18 (Table 3-3). Similarly, number of weekly sessions attended a nd adherence within the first month of treatment were examined in relation to net weight change at Months 1, 6, and 18 and also weight change between Months 6 and 18. First month attendanc e was significantly correlated to net weight change at both one and six months (p < .05 and p < .001, respectively), but not to18 months or change between 6 and 18 months (Table 3-3) Similar results were found for first month adherence rate ( ps < .001; Table 3-3). Initial Rate of Weight Loss and Metabolic Risk Factors At both 6 and 18 months, no significant differences am ong the FAST, MODERATE, and SLOW weight loss groups were found in changes of triglycerides, LDL-c holesterol, systolic blood pressure, and HbA1c levels (all ps > .05; Figure 3-3). As a retrospective analysis, Pearsons correlation coefficients were calculated to assess whether initial weight loss occurring within the first month of treatment was significantly related with net change in any of the metabolic risk factors at both 6 and 18 months. Re sults indicate that only initial rate of weight loss and change in HbA1c from Months 0 to 6 were significantly correlated (r = 0.16, p < .05). Initial Rate of Weight Loss, Attendance, Adh erence, Caloric Intake, and Physical Activity Additional retrospective anal yses were conducted to a ssess whether first-month attendance and adherence were si gnificantly different among wei ght-loss groups. Similarly, oneway ANOVAs were also performed to assess whether the FAST, MODERATE, and SLOW groups differed according to self-reported aver age daily steps (calculated by individual pedometers) and caloric intake within the first month of treatment. Th e homogeneity of variance assumption was violated for both firs t-month attendance and adherence ( ps < .001) and caloric 35

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intake (p < .05); therefore, the Brown-Forsythe F -ratio is reported. Both attendance and adherence within the first month of behavioral treatment were f ound to be significantly different among weight-loss groups ( F (2, 205) = 3.78, p < .05, r = .17 and F (2, 123.1) = 19.13, p < .001, r = .37, respectively; Table 3-4). Bonferroni-corrected comparisons indicate that differences in first-month attendance approached significance for the SLOW versus FAST groups (p = .052). With regards to adherence, post-hoc analys es indicated that the SLOW group completed significantly fewer food record s than did women in both th e FAST and MODERATE groups, and the MODERATE group completed significantly fewer records than the FAST group ( ps < .001). No significant differences were found among the groups on average daily caloric intake ( p = .32) or average number of daily steps ( p = .07) within the first m onth of treatment (Table 34). However, results of one-way ANOV As assessing differences among the FAST, MODERATE, and SLOW groups in cal oric intake and steps solely during the fourth week of treatment indicate groups did begin to diverge. Both caloric intake and steps at Week 4 were significantly different among groups (F (2, 183.8) = 10.42, p < .001, r = .29 and F (2, 220) = 3.26, p < .05, r = .17, respectively, Table 3-5) Bonferroni-corrected comp arisons indicate the SLOW group took in significantly more calories th an both the FAST and MODERATE groups ( ps <.001). 36

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Table 3-1. Baseline demographic characteristics of particip ants in FAST, MODERATE, and SLOW groups FAST n = 55 MODERATE n = 96 SLOW n = 79 M SD M SD M SD Age (years) 59.4 6.2 59.1 6.4 58.9 6.2 Weight (kg) 97.2 15.1 96.1 15.0 96.2 15.0 BMI (kg/m) 37.0 4.7 36.8 5.1 36.6 4.9 n % n % n % Race/ethnicity Caucasian 51 92.7 74 77.1* 53 67.1** African American 1 1.8 19 19.8 24 30.4 Hispanic American 2 3.6 1 1.0 2 2.5 Other 1 1.8 2 2.1 0 0.0 Education < 12 years 25 45.5 35 36.5 27 34.2 Some college/ college degree 27 49.1 53 55.2 42 53.2 Post-college 3 5.5 8 8.3 10 12.7 Note: p < .01, ** p < .001 Table 3-2. Pretreatment caloric intake, physical f itness, and metabolic risk factor levels for FAST, MODERATE, and SLOW groups FAST n = 55 MODERATE n = 96 SLOW n = 79 M SD M SD M SD Caloric intake (kcal) 1802.6 662.1 1708.0 676.1 1726.3 617.7 Physical fitness (ft) 1419.5 177.2 1395.4 186.5 1413.7 186.8 Systolic blood pressure (mm Hg) 125.7 10.2 126.1 8.9 124.9 8.9 Triglycerides (mg/dL) 148.8 59.0 148.0 62.3 139.0 65.6 LDL-cholesterol (mg/dL) 124.0 26.8 124.5 30.6 118.2 29.9 HbA1c (%) 5.9 0.5 5.9 0.7 6.0 0.8 37

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Table 3-3. Behavioral co rrelates of weight loss Month 0 to 1 (kg) Month 0 to 6 (kg) Month 0 to 18 (kg) Month 6 to 18 (kg) M + SD r r r r Month 0 to 1 (kg) -1.8 + 1.6 0.58** 0.31** -0.11 First month attendance 3.8 + 0.5 -0.14* -0.23** -0.07 0.11 First month adherence 19.0 + 3.9 -0.34** -0.27** -0.09 0.13 Note: p < .05, ** p < .001 Table 3-4. First month attendance and adhere nce rates for FAST, MODERATE, and SLOW groups FAST n = 55 MODERATE n = 96 SLOW n = 79 M SD M SD M SD Attendance 3.9* 0.4 3.8 0.4 3.6 0.6 Adherence 20.6** 1.3 19.7** 2.7 17.1** 5.4 Calories (kcal) 1444.9 612.4 1391.1 217.0 1496.0 378.1 Steps 4704.0 2133.5 4720.8 2292.5 4006.0 2076.7 Note: p = .052 for FAST vs. SLOW, ** p < .001 for FAST vs. SLOW, FAST vs. MODERATE, and MODERATE vs. SLOW Table 3-5. Week 4 average caloric intake a nd steps for FAST, MODERATE, and SLOW groups FAST n = 55 MODERATE n = 96 SLOW n = 79 M SD M SD M SD Calories (kcal) 1192.7** 196.0 1241.6** 224.1 1378.9 309.3 Steps 5499.6 2410.6 5419.8 2474.1 4580.5 2257.8 Note: ** p < .001 for FAST vs. SLOW and MODERATE vs. SLOW 38

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85.7 88.3 91.5 97.2 83.3 96.1 86.5 96.2 90.3 80.0 82.0 84.0 86.0 88.0 90.0 92.0 94.0 96.0 98.0 100.0 Month 0 Month 6 Month 18kg FAST MODERATE SLOW Figure 3-1. Weight changes according to wei ght-loss group. (Means and Standard Errors) Significant within-group changes were obser ved from Month 0 to 6 and from Month 0 to 18, ps < .001. 39

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40 Figure 3-2. Percentage of weight -loss groups attaining a 10% reduc tion at Month 18. Both the FAST and MODERATE groups were significantly different from the SLOW group. Note: p < .01, ** p < .001. 20.3 38.5* 2** ST MODERATE SLOW 58. 0 10 20 30 40 50 60 70 80 90 100 FAPercent

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41 148.8 128.1 120.7 148.0 134.5 135.8 139.0 125.9 116.5 100 110 120 130 140 150 160 Month 0 Month 6 Month 18mg/dl FAST MODERATE SLOW 124.1 117.3 124.0 115.5 124.5 120.2 125.3 118.2 113.0 105 110 115 120 125 130 Month 0 Month 6 Month 18mg/dl FAST MODERATE SLOW B 125.7 119.0 116.9 126.1 121.1 118.0 124.9 119.9 118.1114 116 118 120 122 124 126 128Month 0 Month 6 Month 18mm Hg FAST MODERATE SLOW 5.6 5.7 6.0 5.6 5.9 5.7 5.9 6.0 5.8 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 6.2 Month 0 Month 6 Month 18% FAST MODERATE SLOW D Figure 3-3. Net changes in metabolic risk fact ors (Means and Standard Errors). A) Trigly cerides. B) LDL-chol esterol. C) Systol ic Blood Pressure. D) HbA1c. A C

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CHAPTER 4 DISCUSSION Primary Aims The present study examined the e ffect of rate of weight lo ss during the first month of a six-month behavioral treatment program on long-term (18-month) success in weight management in obese women ages 50-75. With regards to our primary aims, there were 3 key findings. First, women who lost at FAST ( > 0.68 kg/week [ > 1.5 lb/week]) and MODERATE (< 0.68 and > 0.23 kg/week [< 1.5 and > 0.5 lb/week]) rates during the fi rst four weeks of treatment achieved significantly greater net changes in we ight at both 6 and 18 months than women who lost weight at a SLOW rate (< 0.23 kg/week [< 0.5 lb/week]). These findings are consistent with previous research demonstrating th at larger initial weight losses are associated with greater longterm weight loss success (Astrup & Rssner, 2000 ; Carels et al., 2003; Elfhag & Rssner, 2004; Fogelholm et al., 1999; Jeffery et al.,1998; St otland & Larocque, 2005; Wadden et al., 1992). Specifically, Jeffery et al. (1998) separated a sa mple of 130 men and women into tertiles of maximum achieved weight loss. Those in the hi ghest tertile lost an average 0.68 kg/week while those in the middle and low tertiles lost at sl ower rates (0.58 and 0.29 kg/week, respectively). These rates are comparable to those used in th e present study, illustrating that weight outcomes favor those who initially lose the most weight. Racial differences were observed, with those in the FAST group more likely to be Caucasian th an those in the MODERA TE and SLOW groups. Race/ethnicity was also significantly related to net weight change at six months, but not 18 months, of treatment. These re sults are consistent with previous findings in which African Americans tend to lose weight at a slower in itial rate, but equalize with their Caucasian counterparts later in treatment (Kumanyika et al., 2002; Newton & Perr i, 1997; Wing & Anglin, 1996; Yanovski, Gormally, Lesser, Gwirtsman, & Yanovski, 1994). 42

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Second, it has been well documented that weight loss usually slows following six months of behavioral treatment (Jeffery et al., 2000; Wing, 2002), and wei ght regain begins (Perri, 1998; Wadden et al., 2004). Contrary to the research completed by Jeffery et al. (1998) and others (Sbrocco et al., 1999), participants in the present study who lost at a greate r initial rate did not experience greater amounts of weight regain from end of treatment at six months to 18-month follow-up. This effect could be explained with the present study designs incorporation of a year-long extended care regimen wh ere participants received con tinuing contact. Extended care has been shown to enhance long-term progress (P erri & Corsica, 2002), and it is believed that continuing contact may provide th e overlearning that is necessa ry for long-term habit changes to become fully ingrained for long-term weight loss success (Latner et al., 2000). Other studies that have demonstrated greater weight regain in participants who lose more initially did not incorporate a continuous care model. Because thos e who lose larger amounts of weight are more susceptible to regain (McGuire et al., 1999; Weiss et al., 2007; Wing & Hill, 2001), our results support the notion that overlea rning long-term habit cha nges through extended care is necessary to maintain large initial weight losses. Third, as the National Heart, Lung, and Blood Institute (1998) defined successful weight loss maintenance, the present study examined whet her women who lost wei ght at a SLOW initial rate were more likely to achie ve a 10% weight reduction at 18 month follow-up than those who lost at MODERATE and FAST initial rates. Only 20.3% of the SLOW group attained a 10% weight loss in the year following active beha vioral treatment compared to 38.5% of the MODERATE group and 58.2% of the FAST group. These results do not support the hypothesis that the SLOW group was more likely than th e MODERATE or FAST group to achieve a 10% weight reduction at 18 months. Additionally, odds ratios indicate that those women who lost at 43

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FAST and MODERATE rates were 5.5 and 2.5 times more likely than the SLOW weight losers to achieve a successful 10 % weight loss long-term. Taken together, these results do not support the slow weight loss hypothesis. Losing weight at a SLOW initial rate doe s not appear to lead to greater long-term weight loss and/or to lesser amounts of weight regain. Losing at a slow initial rate may be less reinforcing to participants than losing at a moderate or fast initial rate. For example, Carels et al. (2003) assessed quality of life factors, such as general appearance and body image, physical mobility, energy, and perceived health, duri ng the fourth week of a wei ght loss treatment program and found that improvement on these variables were positiv ely associated with weight loss at end of treatment. Therefore, satisfactory early initial weight loss and the related positive quality of life changes may serve as reinforcers/motivators, increasing healthy behaviors and healthy habit learning, and leading to successful weight loss maintenance. Conversely, unsatisfactory early weight loss has been associated with poor tr eatment outcomes (Carels et al., 2003; Wadden & Letizia, 1992). This suggests that when the sh aping of healthy behavior occurs slowly, the changes may be too small, and therefore the re inforcement value may not be great enough to promote learning and long-term habit change. Secondary Aims Attendance and Adherence With regards to our secondary aims, week ly attendance during th e first month of the weight-loss treatment was found to be related to net weight change at both one and six months. These findings support results from previous studie s, suggesting that good attendance within the first few weeks of treatment is associated with better weight loss outcomes at the end of the treatment period (Carels et al ., 2003; Wadden et al., 1992). Howe ver, we did not find that 44

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attendance within the first month of treatment co rrelated with weight maintenance at 18 months. When assessing attendance througho ut the entirety of treatment programs, others have shown that percentage of sessions attended serves as a good predictor of success at one-year follow-up (Wadden et al., 1992). This suggests that, for the present study, assessing attendance within the initial four weeks of the six-m onth program may not have been a sufficient time period to predict 18-month weight loss. Adherence, as measured by number of co mpleted self-monitoring daily food records, during the first month of active treatment was also associated with net weight change at both one and six months. Results are consistent with the argument that self -monitoring of caloric intake is one of the most critical components of behavioral weight-loss treatment (Baker & Kirschenbaum, 1993; Boutelle & Kirsche nbaum, 1998; Brownell, 2000; Wing, 1998). Participants who lost weight at a SLOW initial rate turned in significantly fewer food records during the first month of treatment than did women in the FAST and MODERATE weight loss groups, highlighting the importance of this behavior. However, th is could also be related to attendance in that those who were absent did no t turn in food records. As with attendance, adherence during the first month of treatment wa s not related to 18-month net weight change, once again suggesting that four w eeks may not serve as a sufficient time period for this variable to predict long-term success. Additionally, daily average num ber of steps and calories within the first month of treatment did not differ among groups; however, an assessment of these variables solely during Week 4 of the treatment program indicated that the groups did begin to diverge, with the FAST and MODERATE groups taking in significantly fewer calories a nd recording a higher average number of steps than the SLOW group. Together results of attendance, adherence, caloric 45

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intake, and steps suggest that women who lost we ight at a SLOW initial rate may have been less motivated to make large behavioral changes th an those who lost at both MODERATE and FAST initial rates. Metabolic Risk Factors Finally, the present study al so explored whether differen ces exist among our weight loss groups with regards to metabolic parameters. At both 6 and 18 months, we found no difference in triglycerides, LDL-cholesterol, systol ic blood pressure, and HbA1c among the FAST, MODERATE, and SLOW groups. Additionally, we found that rate of we ight loss within the first month of treatment correlated only with ne t change in HbA1c at six months. No other correlations between rate of weight loss within th e first month and net change in metabolic risk factors existed at either 6 or 18 months. Others have found similar result s in that weight loss during an initial four week pe riod did not influence two year changes in cardiovascular risk factors (Rissanen, Lean, Rssner, Segal, & Sjs trm, 2003). While larg e randomized clinical trials like the DPP (Diabetes Prevention Program Research Gr oup, 2002) and TOHP (Stevens et al., 2001) showed that modest weight changes can re sult in beneficial changes in health related parameters, our results suggest that four weeks may not be su fficient in predicting long-term changes in metabolic risk factors. Limitations There are four potential limitati ons to the present study. Firs t, this study did not employ a prospective, randomized design to assign par ticipants to the FAST, MODERATE, and SLOW weight-loss categories. Our results are consistent with previous studies that indicate a greater initial rate of weight loss l eads to long-term success (Astr up & Rssner, 2000; Carels et al., 2003; Elfhag & Rssner, 2004; Fogelholm et al., 1999; Jeffery et al.,1998; Stotland & Larocque, 2005; Wadden et al., 1992). However, there is some evidence that prescribing faster initial rates 46

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of weight loss may not produce better long-term outcomes. For example, Toubro and Astrup (1997) prospectively randomized one group of obese women to eight weeks of low energy diet (500 kcal/day) and another group to 17 weeks of a conventional hypocaloric diet (1200 kcal/day) so as to achieve similar weight losses at varying rates. Those on the low energy diet experienced weight loss at approximately tw ice the rate of the conventiona l dieters, but groups did not significantly differ in weight maintenance measur ed at one year follow-up. Similarly, Wadden and colleagues (1994) randomly assi gned women to either a balanced deficit diet (1200 kcal/day) condition for 52 weeks of a behavioral treatment program or to a very-l ow-calorie diet (420 kcal/day) for the initial 16 weeks and a balanced deficit diet thereafter. At six months, women on the very-low-calorie diet experienced nearly twice the initial weight loss as those on the balanced deficit diet; however, during the following year of extended care, women who were prescribed the very-low-calorie diet regained significantly more weight. At 18 month follow-up, the groups no longer differed with regards to net weight loss. These results suggest that utilizing methods to attain fast initial weight losses may not lead to successful long-term weight maintenance. A second limitation of the current study i nvolved its limited assessment of how the weight-loss groups achieved their initial rates of weight loss. While associations were found between one-month rate of weight loss and both one-month attendance and adherence, and significant differences were discovered among groups in both caloric intake and steps at Week 4, other factors that constitute significant components for weight-loss lifesty le interventions, such as nutritional content (Nationa l Cholesterol Educa tion Program, 2001), were not formally assessed. 47

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Third, intrinsic motivators, such as change in general appearance, improvement in body image, increased energy, and perceived enhanc ement of health within the first month of behavioral treatment have previously been linked to long-term weight loss success (Carels et al., 2003), but also were not measured in the present study. Therefore it is not possible to separate these additional factors that may affect weight lo ss within the first month of behavioral treatment from rate of weight loss. Future studies that prospectively assign initial rates of weight loss and assess modalities of achieving this weight loss are warranted. Finally, the study is also limited by the population assessed; namely, only women between the ages of 50 and 75 were included in our sample. Generalizability therefore is limited by the exclusion of men and individuals of younger age groups. Additionally, those with serious health conditions, such as hypertension or unc ontrolled diabetes, were excluded from study participation, causing a trun cated range of values for metabolic ri sk factors. This may lead to a floor effect by which participants with less severe metabolic impairment can achieve only incremental reductions and individuals with more significantly elevated risk factors experience greater improvements. Clinical Implications Our study has important clinical implications with regards to behavioral treatments for weight loss. While traditional behavioral tr eatment programs for obesity often result in a reduction of body weight that is associated with cl inically significant bene fits in health-related parameters, weight regain is considered the single greatest challe nge in the long-term management of obesity (Perri, 1998). As Brownell (1984) suggest ed, identifying early predictors of long-term weight loss success could assist in tailoring programs so as to enhance treatment outcomes, but research thus far has illustrated that few of these predictors exist (Teixeira et al., 2005). Results fr om our study support the notion that losing weight at a fast rate 48

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( > 0.68 kg/week [ > 1.5 lb/week]) early in treatment is a strong predictor for long-term weight loss, and that losing at a slow initial rate (< 0.23 kg/week [< 0.5 lb/week]) may be associated with a lower long-term weight loss. Additiona lly, this study provides unique evidence that suggests, within the context of lifestyle treatment where ener gy intake exceeds 1000 kcal/day, the amount of weight regain does not differ based upon early rates of weight loss. Losing weight at a fast initial rate was not associated with greater relapse following active treatment when compared to those who lost lesser weight at a slow er initial rate. It is therefore suggested that substantial efforts be focused on the first fe w weeks of behavioral weight-loss treatment programs. Because small behavioral changes earl y in treatment may not provide enough reinforcement value (i.e. slow weight loss) to result in long-term ha bit change, leaders of lifestyle interventions should enc ourage and motivate participants to make significant behavioral and environmental changes within the first month of the program so as to induce high rates of weight loss. The experience of observing a rapid change in body we ight may serve as a reinforcer, resulting in a faster rate of hab it change and greater l ong-term weight loss. Participants should also be rein forced for attendance and adheren ce as those two variables were found to be related to first month weight change. In sum, these findings suggest that, within the context of a lifestyle treatment, a high rate of initial weight loss is associated with long-term success in weight management. 49

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BIOGRAPHICAL SKETCH Lisa Marie Nackers was born on February 11, 1982 in Appleton, Wisconsin. Her family owned a farm in Wrightstown, Wisconsin, wher e she worked while growing up with both an older and younger brother. She graduated from Wrightstown High School in 2000. She attended college at the University of WisconsinEau Claire and took the opportunity to study abroad for a semester in Dalkeith, Scotland. In 2004, Lisa graduated summa cum laude with a B.A. in psychology and accepted an Intramural Research Training Award fellowship at the National Institute of Diabetes and Diges tive and Kidney Diseases within th e National Institutes of Health (NIH). She conducted basic research on the metabolic functions of the G s protein in mice for one year before accepting another NIH fellowship at the National Center for Complementary and Alternative Medicine. Here, she spent one year assessing neuroendocrine function in men with osteoarthritis pain. In fall 2006, Lisa entered the doctorate program in clinical & health psychology at the University of Florida and is cu rrently researching weight loss interventions for obesity. In conjunction with pursu ing her Ph.D., Lisa is also wo rking toward her masters in public health at the University of Florida. 58