Energy Balance Weight Regulation Study

Study Overview
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Brief Summary
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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
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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.

Official Title
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Energy and Appetite Regulation by High and Low CHO Diets

Conditions
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Obesity

Intervention / Treatment
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* Other: Ad libitum low carbohydrate diet
* Other: Ad libitum High Complex Carbohydrate Diet
* Other: Energy-restricted high complex carbohydrate diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI 30-50 kg/m2 Age 21-65 years Relative good health Exclusion Criteria: Major debilitating mental of physical illness that would interfere with participation Renal or hepatic disease, diabetes, gallbladder disease, untreated hyper-or hypothyroidism, poorly controlled hypertension (>3 HT medications) Use of lipid lowering medications Current of recent (within 12 mo) pregnancy or lactation Current excessive use of alcohol Current/recent (within 1 year)use of tobacco products Food allergies, food restrictions, or food preferences that are inconsistent with the research diets

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Ad libitum low carbohydrate diet | Other: Ad libitum low carbohydrate diet<br>* 6 week ad libitum low carbohydrate diet<br>* Other names: Low Carb diet;|
| Experimental: 2<br>Ad libitum high complex carbohydrate diet | Other: Ad libitum High Complex Carbohydrate Diet<br>* 6 week ad libitum high complex carbohydrate diet<br>* Other names: DASH diet;|
| Experimental: 3<br>Energy-restricted high complex carbohydrate diet | Other: Energy-restricted high complex carbohydrate diet<br>* 6 week energy-restricted (68% of estimated energy requirement for weight maintenance) high complex carbohydrate diet.<br>* Other names: Energy-restricted DASH diet;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 24-hour profiles and AUCs of hormones and other factors that influence central appetite and weight regulation (insulin, leptin, ghrelin, PYY, GLP-1). |  | Week 2, week 3 and week 9 of intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Energy intake, hunger and satiety ratings |  | week 2, 3, and 9 of intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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obesity, low carbohydrate diet, high complex carbohydrate diet, weight regulation hormones, hunger, satiety, energy expenditure, body composition, weight loss