Diet Order Effects of Low Fat vs. Low Carb Diets on Body Fat Change
Who can join
As published by the study on ClinicalTrials.gov. "Not stated" means the study hasn't said — ask the study team.
- Age
- 18 Years to 50 Years
- Sex
- All sexes
- Healthy volunteers
- Not accepted
- Compensation
- Not stated
Other requirements are listed under Eligibility below. Only the study team can confirm whether you can join.
What to expect
No one can promise a trial will help you personally — that is what the research is trying to find out.
What participation involves
- Visits mentioned: 3 visits, 2 visits
- Time periods mentioned: 4 weeks
- Procedures mentioned: Urine samples, Wearing a device, X-rays
Only what the study's summary and detailed description on ClinicalTrials.gov say. Time periods may describe the whole study or a part of it — ask the study team what applies to you.
Show the study's own words
- "Objective: To test the effects of diet order in people receiving either a low-fat or low-carbohydrate diet first for 4 weeks and then immediately switched to the other diet for another 4 weeks."
- "Design: Participants will complete the study at their homes, but there will be 3 required visits to the NIH."
- "Participants will drink a special type of water 2 weeks before the baseline NIH visit and collect urine samples at home to measure how many calories they burn."
- "They will give stool, blood, and urine samples."
- "Participants will be asked to eat a specific diet for 4 weeks followed by a different diet for 4 weeks."
- "They will wear a monitor to track their physical activity and a sensor to measure their glucose levels."
- Compensation
- Not stated
- Study-related exams and procedures are typically provided at no cost. This is how many trials work in general — confirm the details for this study with the study team.
- Participants are monitored closely by the research team throughout the study.
- Some participants may receive access to an investigational treatment, which is still being studied.
- Your participation helps researchers learn whether this approach could help future patients.
About this study
In plain language
This study tests whether starting with a low-fat or low-carb diet leads to more body fat loss. Adults with a body mass index (BMI) of 25 or higher will follow each diet for 4 weeks at home, with meals delivered and 3 visits to the NIH.
Background: In a previous study, participants were lived at the NIH and randomly received either a low-fat or a low-carbohydrate diet for 2 weeks and then switched to the other diet for 2 more weeks. Participants who received the low-carbohydrate diet first lost more body fat at the end of the study than those who received the low-fat diet first. Researchers want to see if they can repeat that result in a longer weight loss study when participants live at home. Objective: To test the effects of diet order in people receiving either a low-fat or low-carbohydrate diet first for 4 weeks and then immediately switched to the other diet for another 4 weeks. Eligibility: Adults aged 19 to 50 years with a body mass index of 25 or more. Design: Participants will complete the study at their homes, but there will be 3 required visits to the NIH. Participants will drink a special type of water 2 weeks before the baseline NIH visit and collect urine samples at home to measure how many calories they burn. Before the diets begin, participants will visit the NIH for baseline testing when they will have a metabolism test while relaxing in a bed with a plastic hood over their head to collect the air they breathe out. They will have scans to measure their bone density and how much muscle and body fat they have. They will give stool, blood, and urine samples. Participants will be asked to eat a specific diet for 4 weeks followed by a different diet for 4 weeks. All meals will be delivered to the participants' homes. They will eat only the foods delivered. Participants will weigh themselves daily. They will wear a monitor to track their physical activity and a sensor to measure their glucose levels. They will prick their finger each morning to test a drop of blood for ketones. Participants will meet virtually as a group with the study team weekly. Participants will have two more NIH visits towards the end of each diet period....
Compensation is read from the study's own description and may be missing — always confirm with the study team.
Eligibility
Who can join
- Be age 18–50 under the detailed rules. The study overview lists ages 19–50.
- Have a BMI of 25 or higher. BMI is a measure based on height and weight.
- Have had less than a 5% change in weight over the past 6 months.
- Be willing and able to follow all study steps and lifestyle rules for the full study.
Who can't join
- Have a pacemaker or another implant that could affect the body scan, or lack enough fridge space or a suitable microwave.
- Have a condition that affects appetite or the immune system, or take drugs that affect how the body uses energy. The study team may also exclude people for other health conditions.
- Be unable to keep a steady routine, avoid travel, or avoid outside foods and certain supplements. Strict food rules, food allergies, or disliking many study foods may also prevent joining.
- Be pregnant, breastfeeding, unable or unwilling to use birth control during the study, or have signs of menopause or the years leading up to it.
- Do more than 150 minutes of hard exercise a week or drink more than 3 alcoholic drinks a day. Regular tobacco, nicotine replacement, or illegal drug use in the past 6 months, or a urine drug test result, may also prevent joining.
- Have a mental health condition that makes study participation unsafe or unlikely to succeed, as judged by the study team.
- Be unable or unwilling to give informed consent, meaning agreement after learning about the study, or not speak English.
- Have a resting energy test result within 10% of 2,500 calories. This test measures how much energy your body uses at rest.
Simplified for readability. The official criteria below are what the study team uses.
Official eligibility criteria
* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: 1. Stated willingness to comply with all study procedures and availability for the duration of the study 2. Adults aged 18-50 years 3. Weight stable (\< +/- 5% over past 6 months) as determined by volunteer report 4. Body mass index (BMI) \>= 25 kg/m\^2 5. Agreement to adhere to Lifestyle Considerations throughout the study duration EXCLUSION CRITERIA: 1. Subjects with cardiac pacemakers or other implants that may be affected by or affect the DXA measurements 2. Inadequate access to equipment required for the study (e.g., too little refrigerator storage space or a microwave oven that is too small) as determined by discretion of PI and/or study team 3. Evidence of diseases or conditions that may influence appetite (e.g., cancer, diabetes, alterations of smell or taste post COVID-19), diseases or conditions that affect the immune system, or other conditions at the discretion of the PI and/or study team 4. Taking prescription medications or other drugs that may influence metabolism (including but not limited to diet/weight-loss medication, some psychiatric medications, or other medications at the discretion of the PI and/or study team) 5. People unlikely to adhere to a relatively consistent daily and weekly routine and avoid travel during their participation in the study. For example, people with occupations such as pilots, flight attendants, or frequently travel for work or pleasure. 6. People unlikely to abstain from off study food or supplements that may impact metabolism or appetite at the discretion of the study team 7. Positive pregnancy test or lactating as determined by volunteer report (women only) 8. Inability or unwillingness to use birth control between screening and completion of the study (women only) 9. Symptoms or signs of perimenopause or menopause by volunteer report (women only) 10. Regular vigorous exercise \>150 min per week as determined by volunteer report 11. Alcohol consumption \> 3 drinks per day as determined by volunteer report 12. Regular use of tobacco (smoking, chewing, or vaping), nicotine replacement therapy, or illicit drugs over past 6 months as determined by volunteer report. Subjects may also be excluded based on a urine drug test. 13. Psychological conditions as determined by DSM-5 Self-rated Level 1 Cross-cutting Symptom Measure such as (but not limited to) eating disorders, depression, bipolar disorders, that would be incompatible with safe and successful participation in this study, as determined by investigators 14. Volunteers with strict dietary concerns (e.g. vegetarian or kosher diet, food allergies) or a reported dislike of a significant fraction of the study foods 15. Volunteers unwilling or unable to give informed consent 16. Non-English speakers due to unavailability of required questionnaires in other languages 17. Resting Energy Expenditure test result within 10% of the 2500 calorie requirement at rest
Study sites (1)
MD
- National Institutes of Health Clinical Center · Bethesda, MD 20892Valerie Darcey · Study contact · 301-402-9689 · valerie.darcey@nih.govMore trials in Bethesda