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Macronutrients and Body Fat Accumulation: A Mechanistic Feeding Study
Boston Children’s Hospital, Harvard Medical School,; Indiana University Bloomington; University of Alabama, Birmingham; Framingham State University; Baylor College of Medicine
David S. Ludwig and Cara B. Ebbeling (Boston Children’s Hospital); David B. Allison Indiana University Bloomington
Quick Study Summary
Do Macronutrients Matter for Body Fat Accumulation?
This study is evaluating if the amount or type of carbohydrates consumed contribute to weight gain in a manner that is independent of net calorie intake.
The “calories in, calories out” view of body weight control provides the basis of all conventional weight loss diets (3). To lose weight, just eat less and move more, with treatment focusing on behavioral methods to help people maintain a negative calorie balance.
The Carbohydrate Insulin Model proposes:
- An increased consumption of processed carbohydrates and added sugar predisposes to weight gain by increasing insulin secretion, leading to:
- increased stored body fat
- increased hunger
- slower metabolism
- This theory has not been adequately tested
Biological Adaptations of Weight Loss
What makes it so hard to keep weight off? When we lose weight, our bodies adapt:
- Energy expenditure declines
- Hunger increases
This is a parallel arm randomized-controlled feeding study involving 125 adults with obesity with a Run-In phase and a 2-part Residential Phase.
- Run-In Phase
- Location: “Free-Living” (Outpatient)
- Description: Reduced-calorie, very-low-carbohydrate (ketogenic) diet prepared by Trifecta
- Length: 3 to 4 months
- Purpose: To achieve 15 +/- 3% weight loss
- Residential Phase, Part 1
- Location: Secluded residential setting allowing strict control of food intake
- Description: Isocaloric diet (equal calorie intake and expenditure ) with meals prepared under the direction of an executive chef
- Length: 3 weeks
- Purpose: To carefully measure individual components of energy expenditure with the goal of attaining precise energy balance
- Residential Phase, Part 2
- Location: same
- Description: Participants will be randomized to one of the 3 energy balanced test diets, varying in carbohydrate and sugar:
- normal carbohydrate/low sugar
- normal carbohydrate/normal sugar
- Length: 10 weeks
- Purpose: To test the study hypotheses
- To determine whether amount or type of dietary carbohydrate alters body composition while controlling for energy intake
- To determine whether amount or type of dietary carbohydrate alters energy expenditure while controlling for energy intake
- To determine whether amount or type of dietary carbohydrate alters chronic disease risk factors while controlling for energy intake
- To explore physiological mechanisms relating amount or type of dietary carbohydrate to body composition, energy metabolism, and risk for chronic disease.