NCT06325722

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

Recruiting now NA Last updated 31 March 2026

What this trial tests

NA trial testing Low-carbohydrate Diet in Overweight in 42 participants. Currently enrolling.

Timeline

28 August 2024

Primary endpoint
31 July 2026

31 July 2026

Quick facts

Lead sponsor	National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Phase	NA
Status	Recruiting now
Study type	INTERVENTIONAL
Allocation	randomized
Design	crossover
Masking	single
Primary purpose	basic science
Enrollment	42
Start date	28 August 2024
Primary completion	31 July 2026
Estimated completion	31 July 2026
Sites	1 location across United States

Drugs / interventions tested

• Low-carbohydrate Diet
• Low-fat Diet

Conditions studied

• Overweight — all drugs for Overweight →
• Obesity — all drugs for Obesity →

Sponsor

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

Who can join

Adults 18 to 50, any sex, with Overweight or Obesity. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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....

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Reply to DS Ludwig et al.
   Hall KD, Sciarrillo CM, Guo J, Hengist A, et al · · 2025 · cited 1× · PMID 39627065 · DOI 10.1016/j.ajcnut.2024.11.005