Effects of Timed Restricted Eating on Body Composition, Metabolism, and Cardiovascular Health

NCT07574177 | Not Yet Recruiting

• 1 other identifier: 2435606-1
• Study Type: interventional
• Target: 60
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study is looking at whether eating all meals within a 6-hour window each day (called Time-Restricted Eating, or TRE) can improve body composition, metabolism, heart health, and blood markers over 12 weeks. The study also wants to find out whether allowing participants to eat normally on weekends makes the diet easier to follow long-term. Adults aged 18-65 with a BMI of 26 or higher who do not have heart disease or diabetes may be eligible. Participants will be randomly placed into one of two groups: (1) TRE every day for 12 weeks, or (2) TRE on weekdays with normal eating on weekends. All participants will visit the lab twice - once at the start and once at the end - for measurements of body fat, resting calorie burn, heart function, and blood tests. Between visits, participants will log their meals and steps at home and check in with the research team every two weeks.

Conditions

Intermittent Fasting

Keywords

Time-Restricted Eating; body composition; obesity; weight management; intermittent fasting

Outcome Measures

Primary Outcomes (1)

• Body Fat Percentage

  Change in body fat percentage assessed via the 4-compartment (4C) model, combining DXA-derived bone mineral content, air displacement plethysmography (BodPod) body volume, bioimpedance spectroscopy (BIS) total body water, and calibrated body mass, using the Wang equation.

  Baseline and 12 weeks

Study Arms (2)

TRE Only

EXPERIMENTAL

Participants restrict all calorie-containing food and beverages to a 6-hour afternoon eating window (e.g., 2-8 pm) every day for 12 weeks. Outside of this window, only water, black coffee, and plain tea are permitted.

Behavioral: Time-Restricted Eating (TRE)

TRE + Weekend Ad Libitum (TRE+IER)

EXPERIMENTAL

Participants restrict all calorie-containing food and beverages to the same 6-hour afternoon eating window Monday through Friday. On Saturday and Sunday, participants return to their regular, unrestricted eating habits. This arm tests whether periodic weekend diet breaks improve long-term dietary adherence while maintaining a meaningful weekly calorie deficit.

Behavioral: Time-Restricted Eating with Intermittent Energy Restriction (TRE+IER)

Interventions

Time-Restricted Eating (TRE) BEHAVIORAL

Participants consume all calorie-containing food and beverages within a 6-hour afternoon eating window (e.g., 2-8 pm) every day for 12 weeks. Outside of this window, only non-caloric beverages (water, black coffee, plain tea) are permitted. No changes to food quality or caloric targets are prescribed.

TRE Only

Time-Restricted Eating with Intermittent Energy Restriction (TRE+IER) BEHAVIORAL

Participants follow the same 6-hour afternoon eating window Monday through Friday. On Saturday and Sunday, participants return to their habitual, unrestricted eating pattern (ad libitum intake). This modified approach introduces periodic weekend diet breaks to assess whether reduced dietary rigidity improves long-term adherence while maintaining a clinically meaningful weekly calorie deficit.

TRE + Weekend Ad Libitum (TRE+IER)

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Between 18 and 65 years of age Body mass index (BMI) of 26 kg/m² or higher (overweight or obese range) Physically inactive, defined as 150 minutes or less of moderate-intensity physical activity per week for the 3 months prior to enrollment No previous history of cardiovascular disease or Type 1 or Type 2 Diabetes Mellitus Not currently taking medications that may affect blood sugar, cholesterol, or body weight (e.g., glucose-lowering drugs, statins, or weight loss medications) Weight stable, defined as no more than 5 kg (about 11 lbs.) of body weight change in the 3 months prior to enrollment Willing and able to follow the study requirements, provide voluntary consent, and complete all study procedures

You may not qualify if:

• Younger than 18 or older than 65 years of age BMI below 26 kg/m² More than 150 minutes per week of moderate-intensity physical activity in the past 3 months History of cardiovascular disease or Type 1 or Type 2 Diabetes Mellitus Currently taking medications that may impact study outcomes Weight change of more than 5 kg in the past 3 months Pregnant, breastfeeding, or planning to become pregnant during the study History of an eating disorder Previous weight loss surgery (e.g., gastric bypass or sleeve gastrectomy) Unable to fast for approximately 18 hours at a time due to a medical condition Currently working night shifts Has a pacemaker or any implanted electronic device (due to bioimpedance spectroscopy testing) Any health condition the research team determines would put the participant at risk

Sponsors & Collaborators

• University of South Alabama: lead

MeSH Terms

Conditions

Intermittent Fasting; Obesity

Condition Hierarchy (Ancestors)

Fasting; Feeding Behavior; Behavior; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: May 1, 2026
• First Posted: May 7, 2026
• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): July 1, 2027
• Last Updated: May 7, 2026

Record last verified: 2026-05