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Obesity/Nutrition Research Center



Principal Investigator: KLEM, MARY L

Rates of obesity and overweight in the U.S. are increasing rapidly, while current weight control programs remain relatively ineffective. A primary' prevention approach, which targets individuals at risk for weight gain, may prove more efficacious. Such prevention programs should include assessment of long-term outcome and, to maximize participation rates, should be tailored to appeal to the at-risk population. The aim of the present study is, therefore, to test the long-term efficacy of two programs for primary prevention of weight gain in normal-weight women aged 25-34, a group at high risk for weight gain, and to assess participation rates in these two treatment formats. Subjects (N=300) responding to recruitment materials will be randomly assigned to 1 of 3 treatment formats (group meetings designed to appeal to women aged 25- 34, correspondence course, no-treatment control). Subjects in the group meeting format and the correspondence course will participate in 24- month behavioral weight gain prevention programs. For all three formats, weight will be assessed at 0, 12, 24 and 36 months. Participation rates for the two active treatments will be assessed at 12 and 24 months. Primary' outcome variables will be the proportions of subjects in each format maintaining baseline weight at 36 months and participation rates for the two active treatments at 12 and 24 months. The proposed research is important because it explicitly focuses on primary prevention of weight gain in individuals at risk for future weight gain. It seeks to determine the long-term efficacy of two such programs and to determine the treatment format which produces the largest participation rates. If efficacious, the interventions can be adapted for use in clinical settings. Determination of participation rates can also be used to increase the population outreach of weight gain prevention programs.


Principal Investigator: KULLER, LEWIS H

The risk and benefits of hormone replacement therapy (HRT) have come under increased concern in recent years because of the results of the HERS and WHI trials, the increased risk of breast cancer, new therapies, i.e., SERMs and lipid lowering drugs, bisphosphorates, and better understanding of hormone metabolism and disease. We have shown in several studies that the potential benefits of HRT are limited by lifestyle, cofactors, specifically weight gain, obesity and increased visceral abdominal fat associated metabolic changes in lipoproteins, inflammatory markers and estrogen metabolites. We are proposing a randomized trial of 500 women, on HRT for at least two years, aged 52-60 years, and three or more years postmenopausal to test whether reduction in waist circumference, triglycerides, dense LDLc, number of LDL particles, CPR, PAI-I by aggressive diet exercise, versus a health education control will decrease progression or result in regression of measures of subclinical vascular disease. The intervention is designed to reduce total fat intake to 17 percent of calories, 1300 kilo calories, and increase moderate activity to 150-240 minutes per week to obtain a 10 percent reduction in weight. The primary endpoint will be a 20 percent or at least a 20 mg decrease in triglyceride levels, a 5 cm decrease in waist circumference, and a 10 percent decrease in LDLc. This will result in changes in subclinical measurements including carotid ultrasound, electron beam computer tomography of the coronary and aorta, pulse wave velocity, endothelial function, and tonometry of the radial artery. NMR spectroscopy of lipoproteins, inflammatory markers, and estrogen metabolites will also be evaluated. Therefore, the primary goal of this trial is the modification of measures of subclinical disease among HRT users.


Principal Investigator: JAKICIC, JOHN M.

The primary goal of this study is to examine the dose-response of exercise on long-term weight loss in overweight adult women. Exercise is a key component of behavioral weight loss programs because of its effect on weight loss, body composition, cardiovascular disease risk factors, and other obesity related diseases such as type 2 diabetes mellitus. Despite these benefits, it is unclear whether there is an optimal exercise duration and/or intensity that will enhance long-term weight loss. The current public health recommendation for physical activity is for individuals to participate in at least 30 minutes of moderate intensity physical activity on most days of the week (approximately 150 minutes per week total). However, it is unclear whether this amount of exercise is adequate for long-term weight loss. Moreover, cross-sectional studies have shown that individuals that have been successful at long-term weight loss participate in levels of physical activity that are greater than the current public health recommendations. The researchers hypothesize that adopting higher levels of exercise duration and/or intensity, coupled with a strong behavioral intervention will enhance long-term weight loss. To test this hypothesis, they propose to recruit 200 overweight women and randomly assign them to one of four treatment groups: (1) moderate intensity, moderate 1000cal/wk duration exercise, (2) vigorous intensity moderate duration exercise, (3) moderate 2000cal/wk intensity, high duration exercise, and (4) vigorous intensity, high duration exercise. All subjects will participate in a 24-month behavioral weight loss program, with subjects attending group meetings and receiving periodic telephone contacts from the weight loss program, with subjects attending group meetings and receiving periodic telephone contacts from the interventionists. In addition, to facilitate the adoption of the exercise protocols, all subjects will be provided with a home treadmill. Assessment of body weight will occur at 0, 6, 12, and 24 months and exercise participation will be measured throughout the program. In addition, body composition, cardiorespiratory fitness, cardiovascular disease risk factors, and mediators of behavior change will occur at 0, 6, 12, and 24 months. The investigators believe that the proposed study will lead to improvements in the long-term treatment of obesity.


Principal Investigator: BURKE, LORA E

Obesity, a chronic disorder affecting one third of the U.S. adult population, is the second leading cause of preventable death and a major contributor to increased health care costs. Even a modest weight loss can ameliorate complications and improve longevity. Although behavioral weight loss results in good short-term success, it is followed by an extremely high rate of recidivism. The primary aim of the present study is to promote long-term weight loss by focusing on the use of a lacto-ovo-vegetarian (LOV) eating plan as a dietary strategy, and also on the role of treatment preference. Clinical studies show that vegetarian eating plans can be followed for sustained periods and can produce significant and sustained weight loss as well as numerous health benefits. Pilot data showed that a vegetarian plan leads to acceptable weight loss. There is also evidence to suggest that use of treatment preference leads to improved adherence and reduced attrition. The proposed study will test if giving participants their preference leads to improved adherence, reduced attrition, improved long-term weight loss. Preference will be crossed with 2 treatment options: standard behavioral treatment and standard behavioral treatment + lacto-ovo-vegetarian eating plan (SBT + LOV). All subjects will receive treatment for 12 months and will complete assessments at baseline, 6, 12, and 18 months. The primary aim will test the interaction between treatment assignment and treatment preference and its effect on the primary outcome, weight change from baseline to 18 months. Secondary outcomes include adherence and serum lipids. This study represents an innovative approach to a serious issue, the failure to maintain long-term weight loss. It will provide important information about the efficacy of a vegetarian eating plan in the treatment of obesity, and will address the criticism of vegetarian studies that suggest that patient self-selection is a critical factor in their reported successful outcomes.

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