The Physiology Of the WEight Reduced State (POWERS) study: design and rationale for assessment of food intake,...

The Physiology Of the WEight Reduced State (POWERS) study is a multi-center NIH-funded clinical trial designed to determine the physiological basis for variability in weight loss maintenance among adults with obesity following participation in a behavioral weight loss program. Two hundred and five healthy adults, aged 25-<60 years, with body mass index 30-<40 kg/m² complete up to four serial assessments (before weight loss; after ≥7% weight loss; and four and 12 months later). This report, one in a five-part series on the POWERS study design, provides the rationale for and description of behavioral measures. Standardized laboratory meals are used to measure energy intake and eating-related behaviors. Behavioral and neurocognitive factors related to eating (e.g., food-choice decision making, taste preferences, reward, self-control) are assessed via computer-based tasks and self-report questionnaires. Functional and structural neuroimaging augment the behavioral assessments by identifying underlying neural circuitry. Psychological factors related to weight regulation (e.g., self-monitoring, stigma, self-efficacy) are assessed via self-report questionnaires. Free-living physical activity and sleep are measured via accelerometry, polysomnography and self-report questionnaires. We will evaluate how changes, integrated values and patterns in these predictors and components of energy intake and energy expenditure contribute to individual variability in weight change during the 12 months following weight loss. We anticipate that extensive phenotyping using sophisticated eating behavior paradigms and assessments of critical components of energy expenditure before and after weight loss will lead to improved predictions of successful weight loss maintenance. This, in turn, will inform more effective treatments for long-term sustained weight loss.