Effects of Low Fat Versus Low Carbohydrate Diets on Energy Metabolism
Effects of Low Fat Versus Low Carbohydrate Diets on Energy Metabolism
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

 ...
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).
-  INCLUSION CRITIERIA:

 1. Adults age 18-50 years, male and female

 2. Weight stable (less than or equal to 5 % over past 6 months) as determined by
 volunteer report

 3. Body mass index (BMI) greater that or equal to 20kg/m2

 4. Body weight greater than or equal to 53 kg

 5. Able to complete daily bouts of stationary cycling at a moderate rate and
 intensity with a HR equal to or greater than 0.3(SqrRoot) (220-age-HRrest)+HRrest
 but not exceeding 0.4(SqrRoot) (220-age-HRrest)+HRrest and no signs of arrhythmia

 EXCLUSION CRITERIA:

 1. Evidence of metabolic or cardiovascular disease, or disease that may influence
 metabolism (e.g. cancer, diabetes, thyroid disease)

 2. Taking any prescription medication or other drug that may influence metabolism (e.g.
 diet/weight-loss medication, asthma medication, blood pressure medication, psychiatric
 medications, corticosteroids, or other medications at the discretion of the PI and/or
 study team)

 3. Positive pregnancy test or lactation as determined by volunteer report (women only)

 4. Participating in a regular exercise program (> 2h/week of vigorous activity) as
 determined by volunteer report

 5. Hematocrit <37% (women only)

 6. Hematocrit < 40% (men only)

 7. Caffeine consumption > 300 mg/day as determined by volunteer report

 8. Regular use of alcohol (> 2 drinks per day), tobacco (smoking or chewing)
 amphetamines, cocaine, heroin, or marijuana over past 6 months as determined by
 volunteer report

 9. Psychological conditions such as (but not limited to) eating disorders,
 claustrophobia, clinical depression, bipolar disorders, that would be incompatible
 with safe and successful participation in this study, as determined by investigators.

 1. Past or present history of eating disorders as determined by volunteer report

 2. Past or present history of claustrophobia since part of the protocol will involve
 being confined to a small room for whole-body indirect calorimetry and being in
 an MRI scanner for liver fat measures

 10. Implants, devices, or foreign objects implanted in the body that interfere with the
 Magnetic Resonance procedures

 11. Volunteers with strict dietary concerns (e.g. vegetarian or kosher diet, food
 allergies)

 12. Volunteers unwilling or unable to give informed consent

 13. Non-English speakers due to unavailability of required questionnaires in other
 languages