Effects of Low Fat Versus Low Carbohydrate Diets on Energy Metabolism
Condition: Healthy; Healthy Volunteers
Study type: Interventional

Summary: 
      Background:

      Researchers want to learn how different diets affect hormone levels, body weight, energy
      expenditure, liver fat, and more. To do this, they will use specialized techniques and food
      plans. This is not a weight loss study.

      Objective:

      To better understand how low-fat and low-carbohydrate foods affect health.

      Eligibility:

      Men and women ages 18-50 who have a stable body weight and can exercise daily

      Design:

      Participants will have a screening visit that lasts 4-6 hours. It will include:

      Medical history

      Physical exam

      Fasting blood and urine tests

      Questionnaires

      Trying foods from the study

      Participants will be admitted to the Clinical Center and will stay for 4 weeks without
      leaving. They can have visitors.

      Participants will wear activity and glucose monitors throughout the study. They will be
      weighed daily and will complete daily exercise. They will eat 3 meals daily, plus snacks.
      They will give urine, saliva, and blood samples. They will fill out questionnaires and rate
      their hunger, appetite, and sense of taste. They will have body scans. For the scans, they
      will lie in a machine that takes X-ray pictures of the body.

      Participants will complete activities to measure how many calories they burn and how the
      diets affect them:

      Participants will drink special liquids to measure calories burned, sugar, and sense of
      taste.

      Participants will wear a plastic hood while resting.

      Participants will stay alone in a special room for 24 hours.

      Participants will eat a low-carb, high-fat diet for 2 weeks and a high-carb, low-fat diet for
      2 weeks.

      Participants may be dismissed if they purposefully use the study to try to change their body
      weight.

      Sponsoring Institution: National Institute of Diabetes and Digestive and Kidney Diseases

      ...
    

Detailed description: 
      Competing theories about obesity and its treatment contrast the relative roles of dietary fat
      versus carbohydrate on promotion of excessive calorie intake. Advocates of low-carbohydrate
      diets propose that diets high in carbohydrates lead to elevated insulin secretion and
      increased calorie intake. Alternatively, proponents of low-fat diets argue that diets high in
      fat promote passive overconsumption due to the high energy density and low satiety index of
      high-fat foods. Therefore, we will conduct a feeding study in 20 adult men and women to
      investigate the differences in ad libitum energy intake resulting from consuming two test
      diets for a pair of 2-week periods in a randomized, crossover design during a single 4-week
      inpatient period. The test diets presented to participants will be matched for calories and
      protein, but the low-carbohydrate diet (approximately10% of calories) will be high in fat
      (approximately75% of calories) whereas the low-fat diet will be high in carbohydrates
      (approximately75% of calories) and low in fat (approximately 10% of calories).
    

Intervention name(s): LCHF diet; LFHC diet
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): low-carbohydrate, high-fat (LCHF)diet; low-fat, high-carbohydrate (LFHC) diet
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Accelerometry; Body Composition; Body Weight Regulation; Calories; Energy Expenditure