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Protocol Details

Effect of Low Fat versus Low Carbohydrate Diets on Energy Metabolism

This study is NOT currently recruiting participants.

Summary | Eligibility | Citations | Contacts




Sponsoring Institute

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Recruitment Detail

Type: Completed Study; data analyses ongoing
Gender: Male & Female
Min Age: 18 Years
Max Age: 50 Years

Referral Letter Required


Population Exclusion(s)

Non-English Speaking;


Body Composition;
Body Weight Regulation;
Energy Expenditure

Recruitment Keyword(s)



Healthy Volunteers

Investigational Drug(s)


Investigational Device(s)



Dietary Supplement: LCHF diet
Dietary Supplement: LFHC diet

Supporting Site

National Institute of Diabetes and Digestive and Kidney Diseases


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.


To better understand how low-fat and low-carbohydrate foods affect health.


Men and women ages 18 50 who have a stable body weight and can exercise daily


Participants will have a screening visit that lasts 4 6 hours. It will include:

Medical history

Physical exam

Fasting blood and urine tests


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

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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


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.

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

b. 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

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Not Provided

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Principal Investigator

Referral Contact

For more information:

Kevin Hall, Ph.D.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
National Institutes of Health
Building 12A
Room 4007
12 South Drive
Bethesda, Maryland 20892
(301) 402-8248

Michael S. Stagliano, C.R.N.P.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
(301) 827-3198

Office of Patient Recruitment
National Institutes of Health Clinical Center (CC)
Building 61, 10 Cloister Court
Bethesda, Maryland 20892
Toll Free: 1-800-411-1222
Local Phone: 301-451-4383
TTY: TTY Users Dial 7-1-1

Clinical Trials Number:


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