Time Restricted Eating for Weight Management

July 24, 2026 updated by: Krista Varady, University of Illinois at Chicago
A 12-month randomized, controlled, parallel-arm trial, divided into 2 consecutive periods: (1) 6-month weight loss period; and (2) 6-month weight maintenance, will be implemented. Adults with obesity will be randomized to 1 of 3 groups: (1) 8h-TRE, ad libitum food intake from 12pm to 8 pm, fasting from 8 pm to 12 pm daily, (2) CR, 25% energy restriction every day; or 3) control, ad libitum food intake daily, eating within more than 10 hours per day.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Time restricted eating (TRE) has become a popular weight loss regimen. The sudden rise in popularity of TRE is mostly likely due to is its sheer simplicity, and the fact that it does not require individuals to count calories in order to lose weight. Participants are simply asked to consume all food within a specified time frame and fast with energy free beverages for the remaining hours of the day. Evidence shows that when people with obesity limit their eating window to 6 to 8 hours per day, they naturally reduce energy intake by 350-500 calories. From a clinical standpoint, these findings are paramount. One of the main reasons for subject attrition with traditional dieting, i.e. daily calorie restriction (CR), is frustration with having to count calories every day. TRE regimens are able to side-step this requirement by allowing participants to simply "watch the clock" instead of monitoring calories, while still producing significant weight loss and metabolic health improvements. This feature of TRE has the potential to improve long-term adherence to the diet, and in turn produce lasting weight control in adults with obesity.

Accordingly, we conducted a one-year, randomized, controlled trial to compare the effects of late TRE (eating all food between 12:00 pm to 8:00 pm, without calorie counting), versus CR (25% energy restriction daily), and a control group eating over a period of 10 or more hours, on body weight and metabolic risk factors in a diverse group of American adults with obesity. We hypothesized that the TRE group would achieve greater weight loss, and experience more pronounced improvements in insulin sensitivity during the 6-month weight loss phase, compared to CR and control participants. We also hypothesized that the TRE group would better maintain their weight loss and sustain their improvements in insulin sensitivity during the 6-month weight maintenance phase, when compared to the CR and control participants.

Study Type

Interventional

Enrollment (Actual)

90

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Illinois
      • Chicago, Illinois, United States, 60612
        • University of Illinois Chicago

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion criteria:

  • Age between 18 to 65 years old
  • BMI between 30 and 50 kg/m2
  • Sedentary or lightly active (<60 minutes/week of light activity for the 3 months prior to the study)

Exclusion criteria:

  • • Type 1 DM or Type 2 DM
  • History of eating disorders (anorexia, bulimia, or binge eating disorder)
  • Are not weight stable for 3 months prior to the beginning of study (weight gain or loss > 4 kg)
  • Are not able to keep a food diary or activity log for 7 consecutive days during screening
  • Are taking drugs that influence study outcomes (weight loss, glucose-lowering medications)
  • Are perimenopausal or have an irregular menstrual cycle (menses that does not appear every 27-32 days)
  • Are eating within less than a 10-hour window at baseline
  • Are pregnant, or trying to become pregnant
  • Are night shift workers
  • Are smokers

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 8-hour Time restricted eating
Ad libitum food intake from 12-8 pm every day Fasting from 8-12 pm every day (16-h fast)
Other: 8-hour Time restricted eating
Ad libitum food intake from 12-8 pm every day Fasting from 8-12 pm every day (16-h fast)
Experimental: Calorie restriction
25% energy restriction every day
Other: Calorie restriction
25% energy restriction every day
No Intervention: Control
Usual diet, Ad libitum intake, eating within >10 hours per day

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Body Weight
Time Frame: Measured at month 0 and 12
Measured by an electronic scale
Measured at month 0 and 12

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Fat Mass
Time Frame: Measured at month 0 and 12
Measured by DXA
Measured at month 0 and 12
Change in Insulin Resistance
Time Frame: Measured at month 0 12
Measured by Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). Values above 2.5 generally considered an indicator of insulin resistance. Higher values indicate greater insulin resistance while lower values indicate lower insulin resistance. HOMA-IR = [glucose (mmol/L) × insulin (μU/L)]/22.5.
Measured at month 0 12
Change in Insulin Sensitivity
Time Frame: Measured at month 0 and 12
Measured by Quantitative Insulin Sensitivity Check Index (QUICKI). QUICKI calculated as = 1/[log (fasting insulin, U/ml) + log (fasting glucose, mg/dl)]. Higher scores (typically > 0.45) indicate high insulin sensitivity. Lower scores (generally ≤ 0.33 or 0.34) indicate decreased insulin sensitivity and an increased risk for insulin resistance or type 2 diabetes.
Measured at month 0 and 12
Change in Fasting Glucose
Time Frame: Measured at month 0 and 12
Measured by a commercial lab (Medstar, IL)
Measured at month 0 and 12
Change in HbA1c
Time Frame: Measured at month 0 and 12
Measured by a commercial lab (Medstar, IL)
Measured at month 0 and 12
Change in Fasting Insulin
Time Frame: Measured at month 0 and 12
Measured by a commercial lab (Medstar, IL)
Measured at month 0 and 12
Change in Systolic Blood Pressure
Time Frame: Measured at month 0 and 12
Measured by a blood pressure cuff
Measured at month 0 and 12
Change in Diastolic Blood Pressure
Time Frame: Measured at month 0 and 12
Measured by a blood pressure cuff
Measured at month 0 and 12
Change in LDL Cholesterol
Time Frame: Measured at month 0 and 12
Measured by a commercial lab (Medstar, IL)
Measured at month 0 and 12

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Illinois at Chicago

Collaborators

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

Investigators

  • Principal Investigator: Krista Varady, PhD, University of Illinois at Chicago

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2021

Primary Completion (Actual)

February 1, 2025

Study Completion (Actual)

February 1, 2025

Study Registration Dates

First Submitted

December 28, 2020

First Submitted That Met QC Criteria

December 30, 2020

First Posted (Actual)

January 5, 2021

Study Record Updates

Last Update Posted (Actual)

July 27, 2026

Last Update Submitted That Met QC Criteria

July 24, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2020-1512
  • R01DK128180 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe