Energy Balance Weight Regulation Study
Condition: Obesity
MeSH terms: Obesity
Study type: Interventional
Phase: Phase 2

Summary: 
      The purpose of this study is to test the hypothesis that a low-carbohydrate diet will impact
      hormones and other factors that regulate appetite and energy balance, and result in lower
      energy intake and greater weight loss, than a high complex carbohydrate diet.
    

Detailed description: 
      The rising epidemic of obesity in the United States is accompanied by widespread public use
      of low carbohydrate diets for weight loss. The popularity of these diets is due partly to the
      promise of a "metabolic advantage" that promotes faster weight loss without an overriding
      sense of hunger. If this claim is true, we hypothesize that a low-carbohydrate diet will
      impact hormones and other factors that regulate appetite and energy balance, and result in
      lower energy intake and greater weight loss, than a high complex carbohydrate diet. To test
      this hypothesis, we will conduct a randomized, controlled feeding trial in which obese adults
      will be randomly assigned to one of three interventions: a low-carbohydrate-ad libitum diet,
      a high-carbohydrate-ad libitum diet, or a high-carbohydrate-energy-restricted diet. The
      low-carbohydrate diet will be modeled after the Induction Phase of the Atkins Diet. The high
      carbohydrate diet will be based on the "Dietary Approaches to Stop Hypertension (DASH)" diet.
      Participants will eat a standardized weight maintenance diet for 3 weeks. Then, for 6-weeks,
      participants assigned to either ad libitum group will be given their assigned diet at 120% of
      there estimated energy needs to maintain weight and allowed to eat as much as desired.
      Participants assigned to the energy-restricted group will be provided a DASH diet at 67% of
      their estimated energy needs to maintain weight and asked to eat all foods provided. Food
      intake will be measured daily. Body weight and hunger and satiety scores will be measured
      three times a week. Body composition and energy expenditure will be measured before and after
      the intervention. 24-hour profiles of hormones and other factors that influence central
      appetite and weight regulation (insulin, leptin, ghrelin, PYY, GLP-1) will be measured
      before, and on first and last days of the intervention, to compare acute and chronic
      metabolic effects of the diets. The analysis of primary outcomes will be based on repeated
      measures and longitudinal models methodology. This study offers a unique opportunity to
      explore how extreme differences in dietary composition, before and after weight loss, affect
      components of energy balance and markers of central appetite and weight regulation. These
      results will be used to design hypothesis-driven studies of the identified mediators of
      appetite and weight regulation in response to dietary manipulation.
    

Intervention name(s): Ad libitum low carbohydrate diet; Ad libitum High Complex Carbohydrate Diet; Energy-restricted high complex carbohydrate diet
Intervention type(s): Other; Other; Other
Intervention description(s): 6 week ad libitum low carbohydrate diet; 6 week ad libitum high complex carbohydrate diet; 6 week energy-restricted (68% of estimated energy requirement for weight maintenance) high complex carbohydrate diet.
Other intervention name(s): Low Carb diet; DASH diet; Energy-restricted DASH diet
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: obesity; low carbohydrate diet; high complex carbohydrate diet; weight regulation hormones; hunger; satiety; energy expenditure; body composition; weight loss