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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
 
Am J Med. Author manuscript; available in PMC 2014 March 1.
Published in final edited form as:
PMCID: PMC3574274
NIHMSID: NIHMS419184

The long-term effectiveness of a lifestyle intervention in severely obese individuals

Jessica L. Unick, PhD,1 Daniel Beavers, PhD,2 Dale S. Bond, PhD,1 Jeanne M. Clark, MD, MPH,3 John M. Jakicic, PhD,4 Abbas E. Kitabchi, PhD, MD,5 William C. Knowler, MD, DrPH,6 Thomas A. Wadden, PhD,7 Lynne E. Wagenknecht, DrPH,8 and Rena R. Wing, PhD1, for the Look AHEAD Research Group

Abstract

Objective

Severe obesity (BMI≥40kg/m2) is a serious public health concern. Although bariatric surgery is an efficacious treatment approach, it is limited in reach; thus non-surgical treatment alternatives are needed. We examined the 4-year effects of an intensive lifestyle intervention on body weight and cardiovascular disease risk factors among severely obese, compared to overweight (25≤BMI<30), class I (30≤BMI<35), and class II obese (35≤BMI<40) participants.

Methods

5,145 individuals with type 2 diabetes (45–76 years, BMI≥25kg/m2) were randomized to an intensive lifestyle intervention or diabetes support and education. The lifestyle intervention received a behavioral weight loss program which included group and individuals meetings, a ≥10% weight loss goal, calorie restriction, and increased physical activity. Diabetes support and education received a less intense educational intervention. 4-year changes in body weight and cardiovascular disease risk factors were assessed.

Results

Across BMI categories, 4-year changes in body weight were significantly greater in lifestyle participants compared to diabetes support and education (p’s<0.05). At year 4, severely obese lifestyle participants lost 4.9±8.5% which was similar to class I (4.8±7.2%) and class II obese (4.4±7.6%) and significantly greater than overweight (3.4±7.0%; p<0.05). 4-year changes in LDL-cholesterol, triglycerides, diastolic blood pressure, HbA1c, and blood glucose were similar across BMI categories in lifestyle participants; however the severely obese had less favorable improvements in HDL-cholesterol (3.1±0.4mg/dL) and systolic blood pressure (−1.4±0.7mmHg) compared to the less obese (p’s<0.05).

Conclusion

Lifestyle interventions can result in important long-term weight losses and improvements in cardiovascular disease risk factors among a significant proportion of severely obese individuals.

Keywords: Severe obesity, weight loss, lifestyle intervention, diabetes, cardiovascular disease

INTRODUCTION

In 2009–2010, it was estimated that 6.3% of the United States adult population was severely obese (body mass index (BMI) ≥40kg/m2)1. Moreover, it is expected that the prevalence of severe obesity will nearly double over the next two decades2. This shift in the population weight distribution towards the more extreme ends of obesity is concerning, given the increased risk for cardiovascular disease and all-cause mortality that is associated with this magnitude of excess body weight1, 35. Thus, there is urgency in determining how best to treat this obesity sub-group. While bariatric surgery is a highly efficacious modality67, it currently treats <1% of the eligible population1, 8.

Consequently, there has been renewed interest in examining the efficacy of lifestyle interventions for the treatment of severe obesity and related comorbidities9. Goodpaster et al.10 reported that an intensive lifestyle intervention for severely obese individuals resulted in a 12.1kg weight loss and significant improvements in numerous cardiovascular disease risk factors at 1 year. Furthermore, we reported similar findings in Look AHEAD, a multi-center randomized controlled trial examining the long-term effects (up to 13.5 years) of an intensive lifestyle intervention on weight loss and cardiovascular morbidity and mortality in overweight or obese individuals with type 2 diabetes11. At 1 year, the severely obese lost 11.2kg or 9.0% of initial body weight which was similar to class I (BMI: 30 to < 35kg/m2) and class II (BMI: 35 to < 40kg/m2) obese individuals and greater than the overweight (BMI: 25 to < 30kg/m2). In addition, the improvements in blood pressure, glucose control, and lipids at 1 year were similar across BMI categories12. Together these findings suggest that in the short term, lifestyle interventions are an efficacious treatment approach for individuals with severe obesity. However, whether lifestyle interventions can be an effective long-term weight control strategy for this population remains unclear.

Previous studies in non-severely obese cohorts have demonstrated less than optimal rates of long-term weight maintenance1315. However, to our knowledge, the only study to examine the long-term effects of a behavioral weight loss program in a severely obese cohort was the Louisiana Obese Subjects Study (LOSS)16. This 2-year randomized controlled trial assessed whether primary care physicians could effectively implement a lifestyle weight loss program in this population. Severely obese individuals who completed the program achieved a 13.1% weight loss at 1 year and regained approximately one-quarter of lost weight by Year 2 (9.6% weight loss from baseline), despite continued monthly group meetings and the use of prescription weight loss medications. However, these data were derived from completer’s analyses and are undermined by poor retention rates (51%) at Year 2.

The purpose of the present study was to examine the effects of an intensive lifestyle intervention on body weight and cardiovascular disease risk factors in severely obese individuals over a longer, 4-year period. Moreover, the severely obese were compared to the less obese on each of these parameters. However, it should be noted that our aim was not to compare lifestyle interventions to bariatric surgery. Indeed bariatric surgery results in larger weight losses and improvements in cardiovascular disease risk factors long-term67. However surgical procedures may be limited in reach and many individuals may prefer a less aggressive treatment approach1, 8, 1718. Thus, it is also important that non-surgical treatment approaches to severe obesity are also empirically tested and continually improved upon.

METHODS

Participants

As previously reported, 5,145 individuals from 16 centers were enrolled in the Look AHEAD trial19. Participants had type 2 diabetes, were 45–76 years of age, and had a body mass index (BMI) ≥25kg/m2 (or ≥27kg/m2 if taking insulin). Individuals passed a maximal exercise test at baseline and completed 2 weeks of self-monitoring to demonstrate behavioral adherence. Further inclusion criteria were HbA1c ≤11%, triglycerides <600 mg/dL, and systolic and diastolic blood pressure ≤160 and ≤100 mmHg respectively. Participants provided written informed consent and study procedures were approved by the Institutional Review Board at each site.

Interventions

Participants were randomly assigned within each center to an intensive lifestyle intervention or diabetes support and education intervention. Complete details of the intensive lifestyle intervention have been described elsewhere20. In short, the lifestyle intervention participants were seen weekly during the first six months (3 group and 1 individual meeting), 3 times/month during months 7–12 (2 group and 1 individual meeting), and received one individual face-to-face contact with an interventionist and one telephone contact/month during years 2–4. In addition, 2–3 times/year participants reported to the center weekly for a 6–8 week weight-loss refresher course. The lifestyle participants were given an initial weight loss goal of ≥10% of initial body weight with a study-wide goal of ≥7%. They also received a strong behavioral intervention which utilized strategies such as self-monitoring, problem solving, goal setting, and relapse prevention to modify dietary and exercise behaviors. Individuals were given a calorie goal of 1200–1800 kcal/day and were instructed to reduce dietary fat intake to <30% of total calories from fat, with <10% from saturated fat. To increase dietary adherence, liquid meal replacements were also provided and utilized. Participants were given a 6-month physical activity goal of ≥175 min/week of moderate-to-vigorous intensity exercise similar to brisk walking and were instructed to accumulate this exercise in bouts ≥10 minutes in duration.

A detailed description of the diabetes support and education treatment arm has been published previously21. During each of the first 4 years, diabetes support and education participants were invited to 3 group sessions/year to promote retention. These sessions focused on diet, physical activity, and social support, but did not include the use of behavioral strategies, nor were participants weighed at meetings. Both diabetes support and education participants and intensive lifestyle intervention participants received usual medical care from their personal physicians.

Assessments

Assessments were conducted annually and were completed by certified, blinded staff members. Height, weight, BMI, and blood pressure were measured using standard procedures19. Serum measures were analyzed by the Central Biochemistry Laboratory (Northwest Lipid Research Laboratories, University of Washington, Seattle, WA). Frozen specimens were shipped for the analysis of HbA1c, fasting serum glucose, total triglycerides, high-density lipoproteins (HDL) and low-density lipoproteins (LDL) using methods described elsewhere19.

Statistical Analyses

Participants were divided into baseline BMI categories as follows: overweight (BMI:25 to <30); class I obese (BMI:30 to <35), class II obese (BMI:35 to <40), and class III obese (BMI≥40). To yield unbiased estimates of the intervention effect on outcome measures, participants who underwent gastric bypass surgery were excluded from all analyses on visits occurring after the date of surgery. The number of affected participants at each visit is not presented due to the need to maintain the blinding of investigators. All statistical tests are adjusted by race, gender, and age at baseline. Mixed linear models were used to estimate and compare means of continuous variables across baseline BMI groups. Achievement of weight loss and ADA goals were analyzed using logistic regression at baseline and 4 year visits, testing for interactions when appropriate. Given that the change in medication usage from years 1–4 was similar across BMI categories but the proportion using medications differed at baseline, models analyzing cardiovascular disease risk factor outcomes at 1 and 4 years were adjusted when appropriate for baseline medication usage and baseline cardiovascular disease risk factor values. Repeated measures logistic regression models were utilized to analyze Year 4 goal attainment based on progression from baseline goal status. All pairwise comparisons between groups were adjusted for multiple comparisons using Bonferroni’s method.

RESULTS

The baseline characteristics of study participants stratified by BMI category have previously been reported12 and selected ones are shown in Table 1. In short, severely obese participants were younger, had lower physical activity and fitness, a larger proportion were female, and a similar percentage were classified as being non-Hispanic white (64.1%), compared to those with a BMI<40. Outcome assessments were completed in ≥95% of participants in each BMI category at Year 4 (see primary outcomes manuscript19 for Consort diagram).

Table 1
4-year changes (mean±SE) in cardiovascular disease risk factors for intensive lifestyle intervention participants

Weight change at Year 4

Figure 1 illustrates the trajectory of percent weight change from baseline to Year 4 for both lifestyle intervention and diabetes support and education participants stratified by BMI category. At all BMI levels, lifestyle participants achieved significantly larger weight losses compared to diabetes support and education participants, and the interaction between BMI category and treatment arm was not significant (p=0.684). Moreover, the percent body weight lost by severely obese lifestyle participants at Year 4 (4.9%) was similar to class I (4.8%) and class II obese participants (4.4%) and significantly greater those who were overweight at baseline (3.4%; p<0.05).

Figure 1
Percent change in body weight for intensive lifestyle intervention and diabetes support and education participants stratified by BMI category.

Figure 2 demonstrates the percentage of lifestyle participants achieving a weight loss ≥5%, ≥7%, or ≥10% at Year 4, stratified by BMI category. There was no significant difference between BMI categories using the ≥5% weight loss threshold; however a significantly higher percentage of severely obese participants achieved a ≥7% weight loss when compared to those who were overweight (38% vs. 32%, p<0.05), and more severely obese participants achieved a ≥10% weight loss compared to overweight and class I obese participants (26% vs. 14% or 22% respectively; p<0.05).

Figure 2
Percentage of intensive lifestyle intervention participants in each BMI category achieving a weight loss ≥ 5%, 7%, and 10% at Year 4.

Changes in weight from Year 1 to 4

Although weight regain occurred between Year 1 and 4 in each BMI group, on average severely obese lifestyle participants regained 40.7% of the weight lost at Year 1 whereas the magnitude of regain was 56.5%, 46.7%, and 47.5% for overweight, class I, and class II obese participants respectively. In addition, 47% of severely obese participants who lost ≥10% of their initial body weight at Year 1 maintained this magnitude of weight loss at Year 4. This was similar to class I (40%) and class II obese (41%) participants and significantly greater than those who were overweight (38%, p<0.05). Finally, of those severely obese individuals who lost less than 10% of their initial body weight at Year 1, 13% also achieved ≥10% at Year 4, compared to only 3.9% in the overweight group (p<0.01).

Cardiovascular disease risk factors

Changes in cardiovascular disease risk factors at Year 4 have previously been reported for diabetes support and education participants and intensive lifestyle intervention participants22. Table 1 compares 4-year changes in cardiovascular disease risk factors for lifestyle participants only, stratified by BMI category. The 4-year change in LDL-cholesterol, triglycerides, diastolic blood pressure, HbA1c, and blood glucose did not differ across BMI categories; however, the improvement in HDL-cholesterol was less in the severely obese compared to the overweight (p<0.05). Moreover, the severely obese had a smaller reduction in systolic blood pressure from baseline to Year 4 compared to all other BMI categories (p<0.05).

Lifestyle participants were categorized based upon whether they achieved the American Diabetes Association’s (ADA) goal for HbA1c (<7%), LDL-cholesterol (<100 mg/dL) or blood pressure (<130/80 mmHg) at 4 years. For all three ADA goals, time (p’s <0.001) and BMI category (p’s = 0.02–0.001) significantly predicted goal attainment at Year 4. However the time x BMI category interaction was not significant (p’s = 0.42 – 0.87), suggesting that the probability of goal attainment increased over time among lifestyle participants, with no differences observed across BMI categories. Moreover, severely obese individuals who achieved a 4-year weight loss ≥10% were more likely to meet the goals at Year 4 compared to severely obese individuals who remained weight stable (+/− 2%). Achievement of a ≥10% weight loss at Year 4 significantly increased the likelihood of achieving the ADA goal for HbA1c (OR=3.12; 95% CI: 1.8– 5.4; p<0.001) and blood pressure (OR=2.10; 95% CI: 1.23–3.59; p<0.01) compared to severely obese individuals who were weight stable. However, a ≥10% weight loss did not impact the likelihood of achieving the ADA goal for LDL-cholesterol (OR=0.99; 95% CI: 0.58–1.69; p=0.97). The above-reported odds ratio analyses for achievement of ADA goals among severely obese lifestyle participants were similar to the odds ratios observed among those in lower BMI categories when similar analyses were performed (p’s >0.05).

DISCUSSION

This study demonstrates that severely obese individuals with type 2 diabetes can be effectively treated using an intensive lifestyle intervention, with a significant proportion of individuals meeting weight loss and cardiovascular disease risk factor goals at 4 years. The mean 4.9% weight loss achieved by severely obese lifestyle participants at Year 4 was similar, if not better, than their lighter counterparts. Furthermore, 26% of severely obese lifestyle participants achieved a ≥10% weight loss at Year 4, which was significantly greater than the percentage of overweight or class I obese participants achieving this weight loss goal. Moreover, the magnitude of weight regain between Years 1 and 4 was similar or slightly lower in the severely obese compared to the less overweight. Together, these findings suggest that lifestyle interventions are equally effective at reducing body weight long-term in severely obese and less obese individuals.

Although this was the first study to examine the long-term effects of an outpatient behavioral weight loss program on weight outcomes in a severely obese cohort, the magnitude of weight loss seen at Year 4 (4.9%) was very close to the 4.6% reported by Christiansen et al.23 at 4 years following a 21-week residential weight loss camp for the severely obese. Moreover, 29% of those who participated in the weight loss camp maintained a ≥10% weight loss at Year 4, which is in line with the 26% seen following lifestyle treatment in the current study. These similar weight-related findings across studies may favor less-intensive outpatient lifestyle interventions as a more practical option for severely obese individuals who do not have the necessary financial resources or are unable or unwilling to commit to living in a residential treatment setting. Future studies should directly compare these approaches.

Examination of 4-year changes in cardiovascular disease risk factors revealed that the severely obese and less obese experienced similar improvements in the majority of risk factors, with the exception of HDL-cholesterol and systolic blood pressure. Moreover, the probability of achieving the ADA goal for HbA1c, LDL-cholesterol, and blood pressure increased over time among all intensive lifestyle intervention participants, with no differences observed across BMI categories. Importantly, although the majority of those in the severe obese category remained severely obese at year 4, they still experienced significant and similar improvements in cardiovascular disease risk factors compared to their less obese counterparts. These findings provide support for the use of lifestyle interventions to reduce cardiovascular disease risk in severely obese individuals.

Given that a ≥10% weight loss has consistently improved cardiovascular disease risk in non-severely obese populations2425, this study also examined whether this relationship exists in the severely obese. Achievement of ≥10% weight loss at Year 4 increased the likelihood of meeting the ADA goal for blood pressure and HbA1c by 200% and 300%, respectively, compared to those who remained weight stable over the 4-year period. This finding is clinically meaningful given that lifestyle interventions will likely not result in reductions to normal weight, or even overweight status in this population. However, even modest reductions (≥10%) in body weight among the severely obese can result in significant improvements in health outcomes.

Although the lifestyle intervention favorably influenced body weight and health outcomes among all weight categories, the severely obese experienced smaller improvements in HDL-cholesterol and systolic blood pressure at Year 4 compared to the less obese. Explanations for this finding are unclear. However, it is possible that a larger magnitude of weight loss is necessary to produce larger improvements in these specific risk parameters and achieve normalization of all cardiovascular disease risk factor values. Indeed, larger weight losses (e.g., ≥10%) in this obesity sub-group significantly improved the likelihood of normalizing cardiovascular disease risk factor values. Thus the goal of future interventions should focus on increasing the proportion of individuals meeting or exceeding this magnitude of weight loss to improve outcomes at the group level. One possible strategy would be to identify individuals who fail to meet specific weight loss goals early in the intervention, and develop and implement novel intervention strategies, tailored toward their individual needs.

This study is strengthened by the large sample of severely obese individuals (n=577) who were treated with a lifestyle intervention and the high rates of retention (≥95%) at Year 4. However, there are several limitations. First, findings from this study may not be generalizable to the entire severely obese population, given that participants in this study were older (45–76 years), had type 2 diabetes, and were at the lower end of the severe obesity range (95% of participants had a BMI between 40 and <52.5 kg/m2). Moreover, participants were highly motivated, completing a behavioral run-in and passing a maximal exercise test prior to acceptance into the study. Finally, severely obese and less obese individuals were treated in the same group meetings; thus it is unclear whether similar outcomes would be observed had the severely obese individuals been treated separately.

In conclusion, this study provides initial evidence that an intensive lifestyle intervention can result in significant long-term reductions in body weight among a considerable proportion of individuals with severe obesity. Moreover, modest weight reductions (≥10%) can have a beneficial impact on several cardiovascular disease risk factors even within the context of persistent severe obesity. However for some severely obese participants, risk factors remain elevated even following weight loss and lifestyle treatment. Further research is needed to examine how to improve upon existing lifestyle interventions such that a greater proportion of individuals with severe obesity achieve larger sustained weight losses and related improvements in health outcomes.

Acknowledgments

Role of authors: All authors significantly participated in the preparation of this manuscript

Funding sources: See “Acknowledgements” section

FUNDING/SUPPORT

This study is supported by the Department of Health and Human Services through the following cooperative agreements from the National Institutes of Health: DK57136, DK57149, DK56990, DK57177, DK57171, DK57151, DK57182, DK57131, DK57002, DK57078, DK57154, DK57178, DK57219, DK57008, DK57135, and DK56992. The following federal agencies have contributed support: National Institute of Diabetes and Digestive and Kidney Diseases; National Heart, Lung, and Blood Institute; National Institute of Nursing Research; National Center on Minority Health and Health Disparities; NIH Office of Research on Women’s Health; and the Centers for Disease Control and Prevention. This research was supported in part by the Intramural Research Program of the National Institute of Diabetes and Digestive and Kidney Diseases. The Indian Health Service (I.H.S.) provided personnel, medical oversight, and use of facilities. The opinions expressed in this paper are those of the authors and do not necessarily reflect the views of the I.H.S. or other funding sources.

Additional support was received from The Johns Hopkins Medical Institutions Bayview General Clinical Research Center (M01RR02719); the Massachusetts General Hospital Mallinckrodt General Clinical Research Center and the Massachusetts Institute of Technology General Clinical Research Center (M01RR01066); the University of Colorado Health Sciences Center General Clinical Research Center (M01RR00051) and Clinical Nutrition Research Unit (P30 DK48520); the University of Tennessee at Memphis General Clinical Research Center (M01RR0021140); the University of Pittsburgh General Clinical Research Center (GCRC) (M01RR000056), the Clinical Translational Research Center (CTRC) funded by the Clinical & Translational Science Award (UL1 RR 024153) and NIH grant (DK 046204); the VA Puget Sound Health Care System Medical Research Service, Department of Veterans Affairs; and the Frederic C. Bartter General Clinical Research Center (M01RR01346).

The following organizations have committed to make major contributions to Look AHEAD: FedEx Corporation; Health Management Resources; LifeScan, Inc., a Johnson & Johnson Company; OPTIFAST® of Nestle HealthCare Nutrition, Inc.; Hoffmann-La Roche Inc.; Abbott Nutrition; and Slim-Fast Brand of Unilever North America.

Some of the information contained herein was derived from data provided by the Bureau of Vital Statistics, New York City Department of Health and Mental Hygiene.

TRIAL PERSONNEL

Clinical Sites

The Johns Hopkins Medical Institutions

Frederick L. Brancati, MD, MHS1; Lee Swartz2; Lawrence Cheskin, MD3; Jeanne M. Clark, MD, MPH3; Kerry Stewart, EdD3; Richard Rubin, PhD3; Jean Arceci, RN; Suzanne Ball; Jeanne Charleston, RN; Danielle Diggins; Mia Johnson; Joyce Lambert; Kathy Michalski, RD; Dawn Jiggetts; Chanchai Sapun

Pennington Biomedical Research Center

George A. Bray, MD1; Kristi Rau2; Allison Strate, RN2; Frank L. Greenway, MD3; Donna H. Ryan, MD3; Donald Williamson, PhD3; Brandi Armand, LPN; Jennifer Arceneaux; Amy Bachand, MA; Michelle Begnaud, LDN, RD, CDE; Betsy Berhard; Elizabeth Caderette; Barbara Cerniauskas, LDN, RD, CDE; David Creel, MA; Diane Crow; Crystal Duncan; Helen Guay, LDN, LPC, RD; Carolyn Johnson, Lisa Jones; Nancy Kora; Kelly LaFleur; Kim Landry; Missy Lingle; Jennifer Perault; Cindy Puckett; Mandy Shipp, RD; Marisa Smith; Elizabeth Tucker

The University of Alabama at Birmingham

Cora E. Lewis, MD, MSPH1; Sheikilya Thomas MPH2; Monika Safford, MD3; Vicki DiLillo, PhD; Charlotte Bragg, MS, RD, LD; Amy Dobelstein; Stacey Gilbert, MPH; Stephen Glasser, MD3; Sara Hannum, MA; Anne Hubbell, MS; Jennifer Jones, MA; DeLavallade Lee; Ruth Luketic, MA, MBA, MPH; L. Christie Oden; Janet Raines, MS; Cathy Roche, RN, BSN; Janet Truman; Nita Webb, MA; Casey Azuero, MPH; Jane King, MLT; Andre Morgan

Harvard Center

Massachusetts General Hospital. David M. Nathan, MD1; Enrico Cagliero, MD3; Kathryn Hayward, MD3; Heather Turgeon, RN, BS, CDE2; Linda Delahanty, MS, RD3; Ellen Anderson, MS, RD3; Laurie Bissett, MS, RD; Valerie Goldman, MS, RD; Virginia Harlan, MSW; Theresa Michel, DPT, DSc, CCS; Mary Larkin, RN; Christine Stevens, RN; Kylee Miller, BA; Jimmy Chen, BA; Karen Blumenthal, BA; Gail Winning, BA; Rita Tsay, RD; Helen Cyr, RD; Maria Pinto

Joslin Diabetes Center: Edward S. Horton, MD1; Sharon D. Jackson, MS, RD, CDE2; Osama Hamdy, MD, PhD3; A. Enrique Caballero, MD3; Sarah Bain, BS; Elizabeth Bovaird, BSN, RN; Barbara Fargnoli, MS, RD; Jeanne Spellman, BS, RD; Ann Goebel-Fabbri, PhD; Lori Lambert, MS, RD; Sarah Ledbury, MEd, RD; Maureen Malloy, BS; Kerry Ovalle, MS, RCEP, CDE

Beth Israel Deaconess Medical Center: George Blackburn, MD, PhD1; Christos Mantzoros, MD, DSc3; Ann McNamara, RN; Kristina Spellman, RD

University of Colorado Health Sciences Center

James O. Hill, PhD1; Marsha Miller, MS, RD2; Brent Van Dorsten, PhD3; Judith Regensteiner, PhD3; Ligia Coelho, BS; Paulette Cohrs, RN, BSN; Susan Green; April Hamilton, BS, CCRC; Jere Hamilton, BA; Eugene Leshchinskiy; Lindsey Munkwitz, BS; Loretta Rome, TRS; Terra Worley, BA; Kirstie Craul, RD, CDE; Sheila Smith, BS

Baylor College of Medicine

John P. Foreyt, PhD1; Rebecca S. Reeves, DrPH, RD2; Henry Pownall, PhD3; Ashok Balasubramanyam, MBBS3; Peter Jones, MD3; Michele Burrington, RD, RN; Chu-Huang Chen, MD, PhD3; Allyson Clark Gardner, MS, RD; Molly Gee, MEd, RD; Sharon Griggs; Michelle Hamilton; Veronica Holley; Jayne Joseph, RD; Julieta Palencia, RN; Jennifer Schmidt; Carolyn White

The University of Tennessee Health Science Center

University of Tennessee East. Karen C. Johnson, MD, MPH1; Carolyn Gresham, RN2; Stephanie Connelly, MD, MPH3; Amy Brewer, RD, MS; Mace Coday, PhD; Lisa Jones, RN; Lynne Lichtermann, RN, BSN; Shirley Vosburg, RD, MPH; and J. Lee Taylor, MEd, MBA

University of Tennessee Downtown. Abbas E. Kitabchi, PhD, MD1; Ebenezer Nyenwe, MD3; Helen Lambeth, RN, BSN2; Amy Brewer, MS, RD, LDN; Debra Clark, LPN; Andrea Crisler, MT; Debra Force, MS, RD, LDN; Donna Green, RN; Robert Kores, PhD

University of Minnesota

Robert W. Jeffery, PhD1; Carolyn Thorson, CCRP2; John P. Bantle, MD3; J. Bruce Redmon, MD3; Richard S. Crow, MD3; Scott Crow, MD3; Susan K Raatz, PhD, RD3; Kerrin Brelje, MPH, RD; Carolyne Campbell; Jeanne Carls, MEd; Tara Carmean-Mihm, BA; Julia Devonish, MS; Emily Finch, MA; Anna Fox, MA; Elizabeth Hoelscher, MPH, RD, CHES; La Donna James; Vicki A. Maddy, BS, RD; Therese Ockenden, RN; Birgitta I. Rice, MS, RPh, CHES; Tricia Skarphol, BS; Ann D. Tucker, BA; Mary Susan Voeller, BA; Cara Walcheck, BS, RD

St. Luke’s Roosevelt Hospital Center

Xavier Pi-Sunyer, MD1; Jennifer Patricio, MS2; Stanley Heshka, PhD3; Carmen Pal, MD3; Lynn Allen, MD; Lolline Chong, BS, RD; Marci Gluck, PhD; Diane Hirsch, RNC, MS, CDE; Mary Anne Holowaty, MS, CN; Michelle Horowitz, MS, RD; Nancy Rau, MS, RD, CDE; Dori Brill Steinberg, BS

University of Pennsylvania

Thomas A. Wadden, PhD 1; Barbara J Maschak-Carey, MSN, CDE 2; Robert I. Berkowitz, MD 3; Seth Braunstein, MD, PhD 3; Gary Foster, PhD 3; Henry Glick, PhD 3; Shiriki Kumanyika, PhD, RD, MPH 3; Stanley S. Schwartz, MD 3; Michael Allen, RN; Yuliis Bell; Johanna Brock; Susan Brozena, MD; Ray Carvajal, MA; Helen Chomentowski; Canice Crerand, PhD; Renee Davenport; Andrea Diamond, MS, RD; Anthony Fabricatore, PhD; Lee Goldberg, MD; Louise Hesson, MSN, CRNP; Thomas Hudak, MS; Nayyar Iqbal, MD; LaShanda Jones-Corneille, PhD; Andrew Kao, MD; Robert Kuehnel, PhD; Patricia Lipschutz, MSN; Monica Mullen, RD, MPH

University of Pittsburgh

John M. Jakicic, PhD1, David E. Kelley, MD1; Jacqueline Wesche-Thobaben, RN, BSN, CDE2; Lewis H. Kuller, MD, DrPH3; Andrea Kriska, PhD3; Amy D. Otto, PhD, RD, LDN3, Lin Ewing, PhD, RN3, Mary Korytkowski, MD3, Daniel Edmundowicz, MD3; Monica E. Yamamoto, DrPH, RD, FADA 3; Rebecca Danchenko, BS; Barbara Elnyczky; David O. Garcia, MS; George A. Grove, MS; Patricia H. Harper, MS, RD, LDN; Susan Harrier, BS; Nicole L. Helbling, MS, RN; Diane Ives, MPH; Juliet Mancino, MS, RD, CDE, LDN; Anne Mathews, PhD, RD, LDN; Tracey Y. Murray, BS; Joan R. Ritchea; Susan Urda, BS, CTR; Donna L. Wolf, PhD

The Miriam Hospital/Brown Medical School

Rena R. Wing, PhD1; Renee Bright, MS2; Vincent Pera, MD3; John Jakicic, PhD3; Deborah Tate, PhD3; Amy Gorin, PhD3; Kara Gallagher, PhD3; Amy Bach, PhD; Barbara Bancroft, RN, MS; Anna Bertorelli, MBA, RD; Richard Carey, BS; Tatum Charron, BS; Heather Chenot, MS; Kimberley Chula-Maguire, MS; Pamela Coward, MS, RD; Lisa Cronkite, BS; Julie Currin, MD; Maureen Daly, RN; Caitlin Egan, MS; Erica Ferguson, BS, RD; Linda Foss, MPH; Jennifer Gauvin, BS; Don Kieffer, PhD; Lauren Lessard, BS; Deborah Maier, MS; JP Massaro, BS; Tammy Monk, MS; Rob Nicholson, PhD; Erin Patterson, BS; Suzanne Phelan, PhD; Hollie Raynor, PhD, RD; Douglas Raynor, PhD; Natalie Robinson, MS, RD; Deborah Robles; Jane Tavares, BS

The University of Texas Health Science Center at San Antonio

Steven M. Haffner, MD1; Helen P. Hazuda, Ph.D.1; Maria G. Montez, RN, MSHP, CDE2; Carlos Lorenzo, MD3; Charles F. Coleman, MS, RD; Domingo Granado, RN; Kathy Hathaway, MS, RD; Juan Carlos Isaac, RC, BSN; Nora Ramirez, RN, BSN; Ronda Saenz, MS, RD

VA Puget Sound Health Care System / University of Washington

Steven Kahn MB, ChB1; Brenda Montgomery, RN, MS, CDE2; Robert Knopp, MD3; Edward Lipkin, MD3; Dace Trence, MD3; Terry Barrett, BS; Joli Bartell, BA; Diane Greenberg, PhD; Anne Murillo, BS; Betty Ann Richmond, MEd; Jolanta Socha, BS; April Thomas, MPH, RD; Alan Wesley, BA

Southwestern American Indian Center, Phoenix, Arizona and Shiprock, New Mexico

William C. Knowler, MD, DrPH1; Paula Bolin, RN, MC2; Tina Killean, BS2; Cathy Manus, LPN3; Jonathan Krakoff, MD3; Jeffrey M. Curtis, MD, MPH3; Justin Glass, MD3; Sara Michaels, MD3; Peter H. Bennett, MB, FRCP3; Tina Morgan3; Shandiin Begay, MPH; Paul Bloomquist, MD; Teddy Costa, BS; Bernadita Fallis RN, RHIT, CCS; Jeanette Hermes, MS, RD; Diane F. Hollowbreast; Ruby Johnson; Maria Meacham, BSN, RN, CDE; Julie Nelson, RD; Carol Percy, RN; Patricia Poorthunder; Sandra Sangster; Nancy Scurlock, MSN, ANP-C, CDE; Leigh A. Shovestull, RD, CDE; Janelia Smiley; Katie Toledo, MS, LPC; Christina Tomchee, BA; Darryl Tonemah, PhD

University of Southern California

Anne Peters, MD1; Valerie Ruelas, MSW, LCSW2; Siran Ghazarian Sengardi, MD2; Kathryn (Mandy) Graves Hillstrom, EdD, RD, CDE; Kati Konersman, MA, RD, CDE; Sara Serafin-Dokhan

Coordinating Center

Wake Forest University

Mark A. Espeland, PhD1; Judy L. Bahnson, BA, CCRP3; Lynne E. Wagenknecht, DrPH3; David Reboussin, PhD3; W. Jack Rejeski, PhD3; Alain G. Bertoni, MD, MPH3; Wei Lang, PhD3; Michael S. Lawlor, PhD3; David Lefkowitz, MD3; Gary D. Miller, PhD3; Patrick S. Reynolds, MD3; Paul M. Ribisl, PhD3; Mara Vitolins, DrPH3; Haiying Chen, PhD3; Delia S. West, PhD3; Lawrence M. Friedman, MD3; Brenda L. Craven, MS, CCRP2; Kathy M. Dotson, BA2; Amelia Hodges, BS, CCRP2; Carrie C. Williams, MA, CCRP2; Andrea Anderson, MS; Jerry M. Barnes, MA, Mary Barr; Daniel P. Beavers, PhD; Tara Beckner; Cralen Davis, MS; Thania Del Valle-Fagan, MD; Patricia A. Feeney, MS; Candace Goode; Jason Griffin, BS; Lea Harvin, BS; Patricia Hogan, MS; Sarah A. Gaussoin, MS; Mark King, BS; Kathy Lane, BS; Rebecca H. Neiberg, MS; Michael P. Walkup, MS; Karen Wall, AAS; Terri Windham

Central Resources Centers

DXA Reading Center, University of California at San Francisco

Michael Nevitt, PhD1; Ann Schwartz, PhD2; John Shepherd, PhD3; Michaela Rahorst; Lisa Palermo, MS, MA; Susan Ewing, MS; Cynthia Hayashi; Jason Maeda, MPH

Central Laboratory, Northwest Lipid Metabolism and Diabetes Research Laboratories

Santica M. Marcovina, PhD, ScD1; Jessica Chmielewski2; Vinod Gaur, PhD4

ECG Reading Center, EPICARE, Wake Forest University School of Medicine

Elsayed Z. Soliman MD, MSc, MS1; Ronald J. Prineas, MD, PhD1; Charles Campbell2; Zhu-Ming Zhang, MD3; Teresa Alexander; Lisa Keasler; Susan Hensley; Yabing Li, MD

Diet Assessment Center, University of South Carolina, Arnold School of Public Health, Center for Research in Nutrition and Health Disparities

Robert Moran, PhD1

Hall-Foushee Communications, Inc

Richard Foushee, PhD; Nancy J. Hall, MA

Federal Sponsors

National Institute of Diabetes and Digestive and Kidney Diseases

Mary Evans, PhD; Barbara Harrison, MS; Van S. Hubbard, MD, PhD; Susan Z. Yanovski, MD; Robert Kuczmarski, PhD

National Heart, Lung, and Blood Institute

Lawton S. Cooper, MD, MPH; Peter Kaufman, PhD, FABMR

Centers for Disease Control and Prevention

Edward W. Gregg, PhD; David F. Williamson, PhD; Ping Zhang, PhD

All other Look AHEAD staffs are listed alphabetically by site.

Footnotes

1Principal Investigator

2Program Coordinator

3Co-Investigator

Potential conflicts of interest and financial disclosures: Dr. Jakicic reported serving on the scientific advisory board for Alere Wellbeing, he was the principal investigator on a research grant awarded to the University of Pittsburgh from BodyMedia, Inc., and he received honorarium for a scientific presentation from JennyCraig and Nestle Nutrition Institute. No other authors reported any other conflicts of interest or financial disclosures.

Trial Registration: clinicaltrials.gov Identifier: NCT00017953

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errorsmaybe discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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