NCT06325722

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

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 42 (estimated)
• Sponsor: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) · NIH
• Sex: All
• Age: 18 Years – 50 Years
• Healthy volunteers: Not accepted

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....

Detailed description

Study Description: This is an 8-week crossover outpatient feeding trial of a low carbohydrate versus a low-fat diet, each provided for 4 weeks in random order with no washout period, in adult volunteers with overweight or obesity. Objectives: Primary Objectives: To determine the effect of diet order on the mean total fat mass change in subjects randomized to receive either a low carbohydrate followed by a low fat diet or the reverse order, with each diet lasting for 4 weeks. Secondary Objectives: To determine the effect of diet order on the mean rate of body weight change in subjects randomized to receive either a low carbohydrate followed by a low fat diet or the reverse order, with each diet lasting for 4 weeks and the rate of weight change is measured during the last 2 weeks of each diet. To determine the effect of diet order on mean total body weight change in subjects randomized to receive either a low carbohydrate followed by a low fat diet or the reverse order, with each diet lasting for 4 weeks. Endpoints: Primary Endpoint: Mean total fat mass change measured by dual energy X-ray absorptiometry at baseline and week 8. Secondary Endpoints: Mean rate of weight change by linear mixed modeling of daily weight measurements. Mean total body weight change measured between baseline and week 8.

Conditions

• Overweight
• Obesity

Interventions

Type	Name	Description
OTHER	Low-carbohydrate Diet	Consisting of 15 percent protein, 75 percent fat, and 10 percent carbohydrate
OTHER	Low-fat Diet	Consisting of 15 percent protein, 10 percent fat, and 75 percent carbohydrate

Timeline

• Start date: 2024-08-28
• Primary completion: 2026-07-31
• Completion: 2026-07-31
• First posted: 2024-03-22
• Last updated: 2026-03-31

Locations

1 site across 1 country: United States