Diet Order Effects of Low Fat vs. Low Carb Diets on Body Fat Change

NCT06325722 | Recruiting

• 2 other identifiers: 10001680001680-DK
• Study Type: interventional
• Target: 42
• Locations: 1 country
• Sites: 1

Brief Summary

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....

Conditions

Overweight; Obesity

Keywords

Diet; Body Fat; Nutrition; weight-loss

Outcome Measures

Primary Outcomes (1)

• Change in total fat mass

  Change in total fat mass (kg) as measured by dual energy X-ray absorptiometry (DXA) from baseline to week 8

  8 weeks

Secondary Outcomes (3)

• Rate of body weight change from baseline to week 8

  8 weeks

• Rate of body weight change during low-carbohydrate diet

  Last 2 weeks of low-carbohydrate diet period

• Rate of body weight change during low-fat diet

  Last 2 weeks of low-fat diet period

Study Arms (2)

low-carbohydrate diet then low-fat diet

EXPERIMENTAL

A low-carbohydrate followed by low-fat diet, each lasting for 4 weeks in adults with overweight or obesity

Other: Low-carbohydrate Diet; Other: Low-fat Diet

low-fat diet then low-carbohydrate diet

EXPERIMENTAL

A low-fat followed by low-carbohydrate diet, each lasting for 4 weeks in adults with overweight or obesity

Other: Low-carbohydrate Diet; Other: Low-fat Diet

Interventions

Low-carbohydrate Diet OTHER

Consisting of 15 percent protein, 75 percent fat, and 10 percent carbohydrate

low-carbohydrate diet then low-fat diet; low-fat diet then low-carbohydrate diet

Low-fat Diet OTHER

Consisting of 15 percent protein, 10 percent fat, and 75 percent carbohydrate

low-carbohydrate diet then low-fat diet; low-fat diet then low-carbohydrate diet

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• In order to be eligible to participate in this study, an individual must meet all of the following criteria:
• Stated willingness to comply with all study procedures and availability for the duration of the study
• Adults aged 18-50 years
• Weight stable (\< +/- 5 percent over past 6 months) as determined by volunteer report
• Body mass index (BMI) \>= 25 kg/m\^2
• Agreement to adhere to Lifestyle Considerations throughout the study duration

You may not qualify if:

• Subjects with cardiac pacemakers or other implants that may be affected by or affect the DXA measurements
• 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
• 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
• 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)
• 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.
• People unlikely to abstain from off study food or supplements that may impact metabolism or appetite at the discretion of the study team
• Positive pregnancy test or lactating as determined by volunteer report (women only)
• Inability or unwillingness to use birth control between screening and completion of the study (women only)
• Symptoms or signs of perimenopause or menopause by volunteer report (women only)
• Regular vigorous exercise \>150 min per week as determined by volunteer report
• Alcohol consumption \> 3 drinks per day as determined by volunteer report
• 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.
• 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
• 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
• Volunteers unwilling or unable to give informed consent

Sponsors & Collaborators

• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): lead

Study Sites (1)

National Institutes of Health Clinical Center

Bethesda, Maryland, 20892, United States

RECRUITING

Related Publications (2)

• Sciarrillo CM, Guo J, Hengist A, Darcey VL, Hall KD. Diet order affects energy balance in randomized crossover feeding studies that vary in macronutrients but not ultra-processing. medRxiv [Preprint]. 2023 Oct 4:2023.10.03.23296501. doi: 10.1101/2023.10.03.23296501.

  PMID: 37986904 BACKGROUND

• Hall KD, Guo J, Courville AB, Boring J, Brychta R, Chen KY, Darcey V, Forde CG, Gharib AM, Gallagher I, Howard R, Joseph PV, Milley L, Ouwerkerk R, Raisinger K, Rozga I, Schick A, Stagliano M, Torres S, Walter M, Walter P, Yang S, Chung ST. Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake. Nat Med. 2021 Feb;27(2):344-353. doi: 10.1038/s41591-020-01209-1. Epub 2021 Jan 21.

  PMID: 33479499 BACKGROUND

Related Links

• NIH Clinical Center Detailed Web Page

MeSH Terms

Conditions

Overweight; Obesity; Weight Loss

Interventions

Diet, Carbohydrate-Restricted; Diet, Fat-Restricted

Condition Hierarchy (Ancestors)

Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Body Weight Changes

Intervention Hierarchy (Ancestors)

Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Officials

• Valerie L Darcey

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

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Nan Zhai, C.R.N.P.

CONTACT

(301) 827-3324; nan.zhai@nih.gov

Valerie L Darcey

CONTACT

(301) 402-9689; valerie.darcey@nih.gov

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: NIH
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 21, 2024
• First Posted: March 22, 2024
• Study Start: August 28, 2024
• Primary Completion (Estimated): July 31, 2026
• Study Completion (Estimated): July 31, 2026
• Last Updated: March 31, 2026

Record last verified: 2026-03-26

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, ANALYTIC CODE
• Time Frame: Upon publication in peer reviewed journal
• Access Criteria: Open, general access

Locations

US (1)