Macronutrients and Body Fat Accumulation: A Mechanistic Feeding Study

Investigating the Impact of Carbohydrate Consumption on Body Fat and Metabolism

Recruiting
18 years - 50 years
All
Phase N/A
1 Location

Brief description of study.

This study will evaluate the effects of dietary carbohydrate and sugar consumption, independent of energy content, on body fatness and metabolism in a rigorous feeding study.

Detailed description of study

Many people with obesity can lose weight for a few months, but most have difficulty maintaining weight loss over the long term. Extensive research has shown that weight loss elicits biological adaptations - including a decline in energy expenditure and an increase in hunger - that promote weight regain. However, this observation leaves unanswered why average body weight has recently increased among populations that are mostly genetically stable. According to the Carbohydrate-Insulin Model, increased consumption of processed carbohydrates during the low-fat diet era of the last 40 years has raised the average body weight being defended by biological mechanisms on a population basis. Specifically, the investigators hypothesize that diets high in total carbohydrate (with or without added sugar) acting through increased insulin secretion, alter substrate partitioning toward storage in body fat, leading to increased hunger, slowing metabolism, and accumulation of body fat.
To test this hypothesis, the investigators plan a randomized-controlled feeding study involving 125 adults with obesity. During the run-in phase, participants will be given a hypocaloric very-low-carbohydrate (VLC) diet, with adjustment of energy intake to produce 15 ? 3% weight loss over approximately 3 months on an outpatient basis. After weight stabilization, participants will be admitted to a residential center for 13 weeks. During the first 3 weeks, energy intake and expenditure will be closely monitored during weight-loss maintenance. Then, energy intake will be individually "locked" at levels equal to energy expenditure and participants will be administered one of three randomly-assigned test diets for 10 weeks. The test diets include VLC, High Carbohydrate-Low Sugar (HC-LS), and High Carbohydrate-High Sugar (HC-HS).
Participants will not be paid for their participation.

Eligibility of study

You may be eligible for this study if you meet the following criteria:

  • Conditions: obesity
  • Age: 18 years - 50 years
  • Gender: All

Inclusion Criteria
Willingness to follow a VLC weight-loss diet
Willingness to reside in a research unit for 3 months and eat/drink only provided study foods and beverages
No major food allergies or aversions
Exclusion Criteria
Specialized diets (e.g., for medical or religious reasons)
Chronic use of any medication or dietary supplement that could affect study outcomes (e.g., insulin, metformin, thyroxine)
History of kidney stones
Current diagnosis or history of kidney stones, gout, or gall stones; or removal of gall bladder

Updated on 19 Feb 2024. Study ID: 1709474161

This study investigates the effects of carbohydrate and sugar consumption on body fat and metabolism. Many people with obesity struggle to maintain weight loss due to biological changes like increased hunger and decreased energy use. The study explores the Carbohydrate-Insulin Model, which suggests that high carbohydrate diets may lead to more body fat by increasing insulin, causing hunger and slowing metabolism.

The study involves 125 adults with obesity who will first follow a very-low-carbohydrate diet to lose weight. After stabilizing their weight, participants will stay in a research center for 13 weeks. They will follow one of three diets: very-low-carbohydrate, high-carbohydrate-low-sugar, or high-carbohydrate-high-sugar, with energy intake matched to their energy use.

  • Who can participate: Adults with obesity willing to follow a very-low-carbohydrate diet and reside in a research unit for 3 months may participate. Major food allergies or specialized diets are exclusion criteria.
  • Study details: Participants will adhere to a specific diet plan in the research unit, consuming only provided foods and drinks. They will be randomly assigned to one of three diets with energy intake matched to expenditure.

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