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Contributions of Weight Loss and Increased Physical Fitness to Improvements in Health-Related Quality of Life

Permanent Link: http://ufdc.ufl.edu/UFE0024510/00001

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Title: Contributions of Weight Loss and Increased Physical Fitness to Improvements in Health-Related Quality of Life
Physical Description: 1 online resource (29 p.)
Language: english
Creator: Ross, Kathryn
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: fitness, health, obesity, qol, weight
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: The relative contribution of obesity versus poor fitness to adverse health outcomes and diminished quality of life remains an area of controversy. Indeed, some researchers contend that poor cardiorespiratory fitness represents a greater threat to health and health-related quality of life than excess body weight. We addressed this issue by providing 298 obese 50-75 year-old women with a six-month lifestyle intervention that incorporated a low-calorie eating pattern coupled with an aerobic exercise program consisting of 30 min/day of brisk walking. The results showed that weight loss exhibited a significant individual contribution to improvements in seven of the nine domains of quality of life assessed by the Medical Outcomes Study Short Form (SF-36). With the exception of physical functioning, however, physical fitness did not significantly contribute to improvements beyond the effects weight loss. Moreover, weight loss functioned as a full mediator of the association between increases in physical fitness and improvements in general health, vitality, and change in health relative to the previous year. Collectively, these findings suggest that for treatment-seeking obese individuals, weight loss rather than increased fitness contributes significantly to improvements in health-related quality of life.
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.
Statement of Responsibility: by Kathryn Ross.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Perri, Michael G.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2009-11-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024510:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024510/00001

Material Information

Title: Contributions of Weight Loss and Increased Physical Fitness to Improvements in Health-Related Quality of Life
Physical Description: 1 online resource (29 p.)
Language: english
Creator: Ross, Kathryn
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: fitness, health, obesity, qol, weight
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: The relative contribution of obesity versus poor fitness to adverse health outcomes and diminished quality of life remains an area of controversy. Indeed, some researchers contend that poor cardiorespiratory fitness represents a greater threat to health and health-related quality of life than excess body weight. We addressed this issue by providing 298 obese 50-75 year-old women with a six-month lifestyle intervention that incorporated a low-calorie eating pattern coupled with an aerobic exercise program consisting of 30 min/day of brisk walking. The results showed that weight loss exhibited a significant individual contribution to improvements in seven of the nine domains of quality of life assessed by the Medical Outcomes Study Short Form (SF-36). With the exception of physical functioning, however, physical fitness did not significantly contribute to improvements beyond the effects weight loss. Moreover, weight loss functioned as a full mediator of the association between increases in physical fitness and improvements in general health, vitality, and change in health relative to the previous year. Collectively, these findings suggest that for treatment-seeking obese individuals, weight loss rather than increased fitness contributes significantly to improvements in health-related quality of life.
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.
Statement of Responsibility: by Kathryn Ross.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Perri, Michael G.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2009-11-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024510:00001


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1 CONTRIBUTIONS OF WEIGHT LOSS AND INCREASED PHYSICAL FITNESS TO IMPROVEMENTS IN HEALTH RELATED QUALITY OF LIFE By KATHRYN M. ROSS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009

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2 2009 Kathryn M. Ross

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3 To my parents, Denise and Gary Ross, for their love and encouragement over the years, and to Harris Middleton for always providing support and cups of coffee to keep me going

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4 ACKNOWLEDGMENTS I would like to thank my mentor, Dr. Michael G. Perri, as well as the TOURS staff for their continued support and guidance in the compilation and completion of this thesis This research was supported by grant R18HL73326 from the National Heart, Lung, and Blood Institute.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................................... 4 LIST OF TABLES ................................................................................................................................ 6 ABSTRACT .......................................................................................................................................... 7 CHAPTER 1 INTRODUCTION ......................................................................................................................... 8 Introduction ................................................................................................................................... 8 Current Study ............................................................................................................................... 10 2 METHOD .................................................................................................................................... 11 Participants .................................................................................................................................. 11 Measures ...................................................................................................................................... 11 Weight .................................................................................................................................. 11 Fitness ................................................................................................................................... 12 Health Related Quality of Life ........................................................................................... 12 Procedure ..................................................................................................................................... 12 Statistical analyses ...................................................................................................................... 13 3 RESULTS .................................................................................................................................... 15 4 DISCUSSION .............................................................................................................................. 23 REFERENCES ................................................................................................................................... 26 BIOGRAPHICAL SKETCH ............................................................................................................. 29

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6 LIST OF TABLES Table page 3 1 Mean weight, BMI, physical f itness, and SF 36 subscale scores at baseline and s ix m ont hs ..................................................................................................................................... 18 3 2 Pearson correlations between weight loss (decrease in BMI), increased physical fitness, and improvements in health related quality of life ................................................. 19 3 3 The individual contributions of decreased BMI and increased physical fitness to improvements in SF 36 domains of health related quality of life ...................................... 20

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7 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science CONTRIBUTIONS OF WEIGHT LOSS AND INCREASED PHYSICAL FITNESS TO IMPROVEMENTS IN HEALTH RELATED QUALITY OF LIFE By Kathryn M. Ross May 2009 Chair: Michael G. Perri Major: Psychology The relative contribution of obesity versus poor fitness to adverse health outcomes and diminished quality of life remains an area of controversy. Indeed, some researchers contend that poor cardiorespiratory fitness represents a greater threat to health and health related quality of life than excess body weight. We addressed this issue by providing 298 obese 50 75 year old women with a six -month lifestyle intervention that incorporated a low -calor ie eating pattern coupled with an aerobic exercise program consisting of 30 min/day of brisk walking. The results showed that weight loss exhibited a significant individual contribution to improvements in seven of the nine domains of quality of life asses sed by the Medical Outcomes Study Short Form (SF 36). With the exception of physical functioning, however, physical fitness did not significantly contribute to improvements beyond the effects weight loss. Moreover, weight loss functioned as a full mediat or of the association between increases in physical fitness and improvements in general health, vitality, and change in health relative to the previous year. Collectively, these findings suggest that for treatment -seeking obese individuals, weight loss ra ther than increased fitness contributes significantly to improvements in health related quality of life.

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8 CHAPTER 1 INTRODUCTION Introduction The relative importance of improved fitness versus weight loss in the care of the obese person is unclear. Tradi tionally, excess weight has been viewed as a larger health risk than physical inactivity and thus weight loss has been the primary focus of interventions designed to decrease disease risks associated with obesity. Recently, however, some researchers have provided data showing that physical inactivity may have a greater impact on morbidity and mortality than excess body weight (Blair & Brodney, 1999; LaMonte, Blair, & Church, 2005; Manson et al., 1991; Wei et al., 1999). If increased physical fitness is indeed more important than weight loss for obese individuals, interventions aiming to decrease affected health risks should focus on this goal rather than the traditional goal of weight loss. Most obesity interventions aim to increase both physical fitness and to decrease weight, rendering it difficult to determine the independent contributions of each to improvement in health outcome. Studies investigating the relative contributions of weight loss and physical fitness on heath risks have reported mixed res ults. Some health risks, such as type 2 diabetes, seem to be more adversely influenced by excess body weight (Weinstein et al., 2004), whereas others, such as coronary artery disease, appear to be affected more by poor physical fitness (Wessel et al., 200 4). In this study, we addressed this issue in the context of health related quality of life (HRQL). HRQL provides a general indicator of day to day functioning for individuals; thus measuring change in HRQL associated with obesity treatment allowed us to investigate the effects of weight loss and increased physical fitness across several realms of functioning (e.g., general health, physical functioning, and vitality) rather than concentrate on a single health risk. HRQL has further been shown to be a pre dictor of mortality, such that decreases in HRQL

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9 corresponded with an increased risk of mortality while increases in HRQL corresponded with a decreased risk of mortality (Kroenke, Kubansky, Adler, & Kawachi, 2008). Moreover, the self report nature of HRQL measures allowed us to investigate how participants perceived their improvements in health and daily functioning. Obesity impacts a variety of dimensions of quality of life, including vitality, bodily pain, and even social functioning. Obese individuals report significantly lower HRQL than normal weight individuals (Han, Tijhuis, Lean, & Seidell, 1998; Kolotkin, 1995; Kruger, Bowles, Jones, Ainsworth, & Kohl, 2007). This decrement is most pronounced within physical dimensions of HRQL, such as bodily pain, physical functioning, and vitality than within emotional dimensions such as social functioning, role functioning: emotional and mental health (Doll, Petersen, & Stewart Brown, 2000; Fontaine & Barofsky, 2001; Larsson, Karlsson, & Sullivan, 2002). Signif icant improvements in HRQL have been observed following weight loss in obese individuals (Karlsson, Sjstrm, & Sullivan, 1998). This association has been shown both in studies reporting moderate weight losses of 4 to 8 kg (Fontaine et al., 1999; Jensen, Roy, Buchanan, & Berg, 2004) and studies observing larger weight losses of 20 kg or more (Kral, 1992; Weiner, Datz, Wagner, & Bockhorn, 1999). Physical inactivity has been identified as a significant health risk independent of obesity (Andersen, Schnohr, Schroll, & Hein, 2000; Blair et al., 1996; Villeneuve, Morrison, Craig, & Schaubel, 1998). For example, Kruger et al. (2007) found that inactive adults were three times more likely than active adults to report poor or fair self rated health regardless of body mass index (BMI) category. Furthermore, increases in physical activity have been associated with increases in HRQL (Elavsky et al., 2005). Research suggests that both weight loss and increased fitness lead to increases in HRQL; however, the individual contributions of each have not been

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10 examined. It is unknown whether weight loss or increases in physical fitness produce greater improvements in HRQL for obese individuals. Current Study This study investigated the relative contributions of weight los s and increased physical fitness to changes in HRQL following lifestyle treatment for obesity. We expected that both weight loss and increased fitness would be independently associated with improvements in HRQL. Moreover, we hypothesized an additive eff ect for weight loss and increased fitness such that each would uniquely enhance HRQL for obese persons. We additionally examined possible mediation of improvements in HRQL. We investigated whether, similar to previous results involving mortality and mor bidity data, increased fitness mediated the association between weight loss and increase in HRQL. Second, we investigated the inverse, whether weight loss mediated the relationship between increased fitness and HRQL. As a secondary aim, we examined whet her having large weight losses coupled with small improvements in physical fitness led to larger increases in HRQL than having smaller weight loss paired with large increases in physical fitness. Accordingly, we categorized participants into two groups ba sed on changes in body weight and fitness. Group 1 contained participants who were in the top tertile for weight loss and the bottom tertile for increased fitness. Group 2 contained participants in the bottom tertile for weight loss and the top tertile f or increased fitness. We hypothesized that participants in Group 1 would have significantly greater improvements in HRQL than those in Group 2.

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11 CHAPTER 2 METHOD Participants Participants were 298 women from rural counties who participated in a 6 -month l ifestyle intervention for obesity (Perri et al., 2008). Of those 298 participants, 274 provided data at both baseline and six months. This sample of 274 participants was used for all analyses. Participants were 50 75 years old (mean age = 59.0 years, SD = 6.2), with BMIs between 30 and 50 kg/m2 (mean BMI at baseline was 36.8 kg/m2, SD = 4.8) and were recruited from six medically underserved rural counties in north central Florida. Potential participants were excluded if they weighed over 158.8 kg, had a history of heart attack or stroke, metabolic abnormalities, any musculo -skeletal conditions that limited walking, any major psychiatric disorders, or experienced significant weight loss (i.e., ace and ethnicity, 76.6% of participants were Caucasian, 19.0% were African American, 1.8% were Hispanic, and 2.6% were Asian, Native American, or Pacific Islander. For details regarding recruitment, screening, and attrition, see Perri et al. (2008). Mea sures Weight Participants were weighed at baseline and six months. Weight was measured to the nearest 0.1 kilogram using a calibrated and certified balance beam scale. For each weighing, participants wore light indoor clothing with no shoes. At the tim e of weighing, each participants height was also measured and recorded. These weights and heights were used to compute each participants BMI.

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12 Fitness Physical fitness was measured at baseline and six month assessments using the 6 Minute Walk Test (6MWT; Butland, Pang, Gross, Woodcock, & Geddes, 1982). For this test participants were given the instructions to walk as quickly as possible, without jogging or running, around two cones placed 40 m. apart. Participants were also told they could stop if the y became too tired, but should resume walking as soon as they were able to continue. To adjust for practice effects, at baseline participants were given two trials, on different days, of the 6MWT; only the data from the second trial were used. When testi ng the validity of the 6MWT, researchers found that distances from the 6MWT were significantly correlated to peak oxygen intake (VO2) values from a cycle ergometer test r = 0.73, p < .001 (Turner, Eastwood, Cecins, Hillman, & Jenkins, 2004). Further, Lars son and Reynisdottir (2008) found that with an obese sample, the 6MWT was reliable (r = 0.94 between two trials) and that BMI explained 38% of the variance in distance walked. Health -Related Quality of Life We used the Medical Outcomes Study Short -Form, re ferred to as the SF 36 (Ware, Kosinski, & Gandek, 2000) as a measure of HRQL. The SF 36 includes eight subscales: Vitality, Bodily Pain, General Health, Physical Functioning, Social Functioning, Physical Role Functioning, Emotional Role Functioning, and M ental Health. In addition to these subscales, the SF 36 also included a question asking participants to report the amount of change in their general health over the past year (referred to as Health Transition). The internal consistency of the SF 36 ran ged from .63 to .96 and the test retest reliability ranged from .60 to .81 (Ware et al., 2000). Procedure Participants underwent a six -month lifestyle obesity intervention modeled after the Diabetes Prevention Program (Knowler et al., 2002) consisting of three parts: a low -calorie

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13 eating plan, weekly aerobic exercise goals, and behavior modification. The intervention involved weekly 90-minute group based sessions delivered via Cooperative Extension Service offices, led by a group leader with a bachelors or masters degree in a relevant discipline. Participants were guided in making gradual changes in their eating and physical activity habits. Caloric goals included adherence to a 1200 kcal per day eating plan, reduction in total fats, and increased consum ption of whole grains, fruits, and vegetables. Participants were also encouraged to increase their physical activity by 3000 steps above baseline, or 30 minutes per day of brisk walking, 6 days per week. At the beginning of each session, participants wer e asked to detail their success in meeting their weekly eating and physical activity goals, and at the end they were asked to identify new goals for the next week. Both eating and physical activity goals were given approximately equal attention during dis cussions. Group leaders were trained in problem solving therapy and assisted participants with overcoming obstacles encountered during the program. Further information on this intervention can be found in a previously published paper (Perri et al., 2008) Statistical analyses Pearson product -moment correlations were used to assess the associations between changes in body weight, physical fitness, and HRQL, and hierarchical regressions were used to examine the individual contributions of weight loss and physical fitness to HRQL. Potential issues with collinearity between weight loss and change in physical fitness were addressed by examining the variance inflation factor (VIF), and a commonality analysis was used to investigate the variance explained due t o the combined effects of weight loss and physical fitness. A pre and post -test longitudinal model was used. Baseline values for BMI, physical fitness, and HRQL were entered as Step 1 in the hierarchical regressions. A change score from pre to post te st for each SF 36 domain was created. This involved saving the residual from a

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14 regression using the baseline and post -test scores as the independent and dependent variables, respectively. The residualized change scores for body weight and physical fitnes s were entered as Step 2 and Step 3, respectively. These residualized change scores were also used in the mediation analyses. After examining the individual contributions of weight loss and increased fitness to changes in HRQL, a series of regressions wer e implemented, in accord with Baron and Kennys (1986) mediation method, to assess whether change in weight mediated the association between increased fitness and increases in HRQL. In this analysis, we only included subscales that initially showed a rela tion between physical fitness and HRQL but did not show a unique effect of physical fitness above and beyond the effect of weight change. Finally, an independent -samples t test was used to examine mean differences in Health Transition scores between part icipants in the top tertile for weight loss and the bottom tertile for increased fitness (Group 1) and participants in the bottom tertile for weight loss and the top tertile for increased fitness (Group 2). The Health Transition item was used as the outco me measure for this analysis because it functioned as a general health -change indicator, and thus it provided the clearest view of the change in HRQL due to the intervention.

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15 CHAPTER 3 RESULTS Out of the 274 participants who provided data at baseline and six -months, 234 completed treatment. Participants who completed treatment lost an average of 10 kg during the intervention (this number has not been adjusted for attrition; for full results, including adjusted weight losses, see Perri et al., 2008). Mea ns for each variable (e.g., body weight, physical fitness, and SF 36 scores) at baseline and six months for all 274 participants who provided data at baseline and six months are available in Table 3 1. On average, participants completed 130 daily food and activity records out of 161 possible records. From baseline to six -months, weight loss (as measured by change in BMI) was significantly correlated with all SF 36 subscales except the Physical Role Functioning and Emotional Role Functioning subscales (see Table 3 2 ). Specifically, decreases in weight were associated with improvements in Health Transition, Physical Functioning, Bodily Pain, General Health, Vitality, Social Functioning, and Mental Health scores (all p s < .05). Additionally, improved physical fitness was significantly associated with improvements in Health Transition, Physical Functioning, General Health, and Vitality from baseline to six -months (all p s < .05). For all analyzed regression models, the VIF values ranged from 1.0 to 1.3, well bel ow the recommended cut -off of collinearity was not an issue with the variables used in this study. Further, commonality analyses run for each regression found that variance explained by the combination of weight loss and physical fitness was not significant. A series of hierarchical regressions, controlling for baseline BMI, physical fitness, and HRQL subscale scores, were conducted to examine the individual contributions of weight loss and increa sed physical fitness to change in HRQL. Results are presented in Table 3 3.

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16 Weight loss was significantly associated with improvements in Health Transition, Physical Functioning, Bodily Pain, General Health, Vitality Social Functioning, Physical Role Fu nctioning, and Mental Health (see Table 3 3 ), but was not associated with Emotional Role Functioning, p = 088. Whereas improvement in physical fitness was significantly related to improvement in Physical Functioning, it did not significantly contribute beyond the effects of weight loss to the variance explained for any other of the subscales. Increased physical fitness was correlated with improvements in several HRQL subscales yet this association became non -significant after controlling for weight loss. Therefore, we investigated possible mediation by weight loss. This mediation hypothesis was applicable to the relationships between increased physical fitness and increases in Health Transition, General Health, and Vitality. Mediation was not investiga ted for Physical Role Functioning because neither weight loss nor physical fitness were related after controlling for baseline data, nor for Physical Functioning because physical fitness remained a significant contributor to change above and beyond the eff ect of weight loss. Improvements in physical fitness were found to be significantly associated with improvements in Health Transition, B = .001, SE = .000, p < .01, General Health, B = .012, SE = .005, p < .05, and Vitality scores, B = .014, SE = .007, p < .05, and with weight loss, B = .005, SE = .001, p < .001. After controlling for physical fitness, weight loss was significantly associated with improvements in Health Transition B = .172, SE = .024, p < .001, General Health, B = 1.613, SE = 358, p < .001, and Vitality, B = 2.267, SE = .474, p < .001 scores. Finally, after controlling for weight loss, the association between improvements in physical fitness and improvements in Health Transition, B = .000, SE = .000, p = .35, General Healt h, B = .007, SE = .010, p = .52, and Vitality, B = .002, SE = .007, p = .77 scores became non-

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17 significant. This suggested that weight loss acted as a full mediator for the association between change in physical fitness and change in Health Transition, General Health, and Vitality. Sobel tests confirmed that this mediation was significant for each subscale, z = 4.10, z = 3.35, z = 3.46, respectively, p < .001. A t test was used to detect significant differences between mean scores on the Health Tra nsition domain between participants who lost a large amount of weight but had minor increases in physical fitness (Group 1) and participants who lost smaller amounts of weight but had large increases in physical fitness (Group 2). There were significantly greater improvements in the Health Transition, t (36) = 3.79, p = .001, for the participants in Group 1 compared to participants in Group 2. Thus, large decreases in weight accompanied by small increases in fitness produced greater improvements in a global HRQL change indicator than large increases in fitness coupled with small weight losses.

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18 Table 3 1. Mean w eight, BMI, p hysical fitness, and SF 36 s ubscale s cores at b aseline and s ix m onths Baseline Six Month Variable M M SD SD Weight (kg) 96.3 14.8 87.2 14.6 BMI 36.7 4.9 33.2 4.9 Physical Fitness (steps walked) 1414.0 184.3 1492.4 195.0 SF 36: Health Transition 2.9 0.7 1.9 0.8 SF 36: Physical Functioning 76 18.8 82.5 17.0 SF 36: Role Functioning: Physical 83.5 29.6 83.1 31.5 SF 36: Bodily Pain 71.3 18.9 71 22.7 SF 36: General Health 75.1 15.6 78.8 15.4 SF 36: Vitality 58.5 18.8 66.2 19.0 SF 36: Social Functioning 90.3 15.7 90.4 17.1 SF 36: Role Functioning: Emotional 90 22.8 87.9 26.6 SF 36: Mental Health 82.9 12.4 82.4 14.7

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19 Table 3 2. P earson correlations between w eight l oss ( d ecrease in BMI), i ncreased p hysical fitness, and improvements in health related q uality of l ife Body Mass Index Physical Fitness HRQL Domain r p r p Health Transition .45 .001 .21 .001 Physical Fun ctioning .21 .001 .21 .001 Role Functioning: Physical .11 .060 .12 .057 Bodily Pain .14 .021 .09 .132 General Health .27 .001 .15 .018 Vitality .27 .001 .13 .037 Social Functioning .14 .019 .01 .887 Role Functioning: Emotiona l .01 .17 6 .01 .921 Mental Health .02 .016 .02 .808

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20 Table 3 3. The individual contributions of decreased BMI and increased physical fitness to improvements in SF 36 domains of healthrelated quality of life Domain Variable R R 2 2 p change Hea lth Transition Step 1 .003 .003 .853 BL BMI .046 BL Physical Fitness .027 BL Health Transition .078 Step 2 .210 .207 .000 BMI .457 Step 3 .212 .002 .432 BMI .440 Physical Fitness .048 Physi cal Functioning Step 1 .028 .039 .016 BL BMI .092 BL Physical Fitness .158 BL Physical Functioning .080 Step 2 .086 .048 .000 BMI .218 Step 3 .104 .017 .026 BMI .166 Physical Fitness .145 Bodily Pain Step 1 .010 .010 .477 BL BMI .100 BL Physical Fitness .006 BL Bodily Pain .003 Step 2 .030 .020 .021 BMI .142 Step 3 .030 .001 .700 BMI .133 Physical Fitness .026 General Health Step 1 .016 .016 .256 BL BMI .103 BL Physical Fitness .044 BL General Health .042 Step 2 .103 .087 .000 BMI .297 Step 3 .103 .000 .737 BMI .289 Physical Fitness .022

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21 Table 3 3. Co ntinued Vitality Step 1 .003 .003 .827 BL BMI .032 BL Physical Fitness .038 BL Vitality .019 Step 2 .098 .095 .000 BMI .308 Step 3 .098 .000 .828 BMI .303 Physical Fitness .014 Social F unctioning Step 1 .003 .003 .882 BL BMI .022 BL Physical Fitness .031 BL Social Functioning .039 Step 2 .034 .032 .004 BMI .178 Step 3 .039 .005 .275 BMI .203 Physical Fitness .074 Role Functioning: Emotional Step 1 .004 .004 .766 BL BMI .053 BL Physical Fitness .025 BL RF: Emotional .016 Step 2 .014 .011 .088 BMI .106 Step 3 .021 .007 .181 BMI .073 Physical Fitness .091 Role Functioning: Physical Step 1 .003 .003 .866 BL BMI .030 BL Physical Fitness .034 BL RF: Physical .018 Step 2 .034 .032 .004 BMI .178 Step 3 .039 .005 .275 BMI .203 Physical Fitness .074

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22 Table 3 3. Continued Mental Health Step 1 .006 .006 .644 BL BMI .074 BL Physical Fitness .060 BL Mental Health .022 Step 2 .036 .029 .006 BMI .171 Step 3 .037 .001 .546 BMI .186 Physical Fitness .041

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23 CHAPTER 4 D ISCUSSION In this study, we investigated the relative contributions of weight loss and physical fitness to improvements in health related quality of life (HRQL). We hypothesized that both weight loss and physical fitness would provide unique contributions to improvements in HRQL. We also predicted that participants with large weight losses but modest increases in physical fitness would experience significantly greater improvements in HRQL than participants with s mall weight losses and large increases in physical fitness. The major finding in this study was that weight loss contributed significantly to improvements in seven of the nine key domains of HRQL (i.e., Health Transition, Vitality, Bodily Pain, General He alth, Social Functioning, Emotional Role Functioning, and Mental Health). For these seven domains, increases in fitness did not contribute significantly to enhanced HRQL beyond the effects of weight loss. Further, weight loss was found to mediate the rel ation between physical fitness and increases for two of the HRQL subscales (i.e., General Health, Vitality) and Health Transition. Finally, participants who lost large amounts of weight with little change in physical fitness had significantly greater impr ovements in HRQL (measured by Health Transition) than participants who had smaller weight losses but greater increases in physical fitness. These results suggest that for obese persons, increased fitness in the absence of significant weight loss may not i mprove healthrelated quality of life. This finding differs from results of several previous studies (Brown et al., 2004; Elavsky et al., 2005; Kruger et al., 2007) which demonstrated that higher levels of physical fitness and physical activity were signi ficantly associated with increased HRQL. Several factors could have contributed to this discrepancy. The study by Elavsky et al. (2005) did not correct for body weight, and there may be an

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24 interaction effect between physical fitness and obesity status in regards to HRQL. It is possible that changes in fitness may be more highly valued by normal weight and overweight individuals than obese individuals. Although the studies by Brown et al. (2004) and Kruger et al. (2007) did control for BMI, both utilized cross -sectional data gathered from phone interviews. Thus, no conclusions could be drawn about the association between change in physical activity levels and HRQL; these studies found that individuals who already participated in physical activity had higher HRQL than those who did not. The self report nature of the SF 36 allowed us to investigate how participants percieved their improvements in health and daily functioning. Compared to weight loss, the changes in fitness experienced by participants may have been subtle, particularly because participants in the current study were healthy and free of chronic disease and physical impairment. As it is easier to observe weight loss than increases in fitness, participants may attribute improvements in mobilit y and daily functioning to reduced weight rather than to increased aerobic fitness. The observed changes in HRQL may have been influenced by participants expectations upon entering the program. The sample was comprised of individuals who volunteered to take part in a weight management program. Participants in such interventions are likely more interested in achieving weight loss than in improving their cardiorespiratory fitness (Foster, Wadden, Vogt, & Brewer, 1997). Thus, the strength of the associati on between weight loss and improved HRQL observed in this study may be due, in part, to participants focus on their weight. Beyond participant expectations, changes in physical fitness may be less salient for participants because weight management program s primarily focus on weight loss. Weight management programs typically assess participants weight on a weekly basis (Wing, Tate,

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25 Gorin, Raynor, & Fava, 2006), and participants receive reinforcement from their interventionist, group members, family and fr iends for their weight loss. In contrast, feedback on changes in physical fitness is less frequently provided. One goal of future interventions could be to increase the emphasis on changes in physical activity and fitness in an attempt to increase the positive valence associated with improvements in physical fitness. For example, the provision of more frequent fitness testing and feedback would likely enhance participant attentiveness to their improved physical functioning. Heightened awareness of such improvements may enhance participants HRQL. There were several potential limitations to the current study. First, the sample was comprised of healthy women ages 5075; the findings may not be generalizable to men, younger adults, and obese individuals in poor health. Second, although participants were followed for six months and assessed pre and post treatment, the design of the study was nonetheless correlational. Because participants were not randomly assigned to weight loss and physical fitness co nditions, caution should be used in interpreting cause and effect with respect to the relationship between weight loss, physical fitness, and HRQL. This study contributes significantly to the literature on weight loss, physical fitness, and HRQL in sever al important ways. To our knowledge, this study is the first to examine the unique contributions of weight loss and increases in fitness on HRQL in obese individuals. Our findings demonstrated that, with respect to middle age and older obese women, weigh t loss rather than increased fitness is a more significant contributor to improvements in quality of life.

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29 BIOGRAPHICAL SKETCH Kat hryn M. Ross graduated from Virginia Commonwealth University in 2006 with a B.S. in psychology. At VCU, Kathryn worked as a research assistant in the lab of Suzanne E. Mazzeo, Ph.D., working on studies involving eating disorders and body image. Kathryn's undergrad thesis investigated the harm of etiological ambiguity for obese individuals. Kathryn began working as a statistical analyst for the Virginia Department of Health, Division of W I C. and Family Services, in the spring of 2005, was promoted to th e position of senior statistical analyst in the spring of 2006, and remained in this position until moving to Florida for graduate school. During her time at the Department of Health, Kathryn was involved in several projects investigating overweight and o besity rates among low income children in the Virginia W.I.C. program. In f all 2007, Kathryn came to the University of Florida to continue her education in clinical and health psychology. She worked under the supervision of Michael G. Perri, Ph.D. on thre e lifestyle we ight management interventions and received her M.S. from the University of Florida in the spring of 2009. Kathryn's research interests include behavioral obesity intervention and weight maintenance programs.