Time-Restricted Eating After Bariatric Surgery

NCT07672821 | Recruiting

• 1 other identifier: MUDU-SBE-SS-04
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 2

Brief Summary

This study aims to compare the effects of time-restricted eating (TRE, 16/8) in adults with obesity who have and have not undergone bariatric surgery (BS). The study will include adults aged 18-65 years: those with obesity who have not undergone BS, and those who have experienced insufficient weight loss (IWL) or weight regain (WR) following BS. Both groups will follow a 16:8 time-restricted eating protocol for 6 weeks, with an 8-hour eating window recommended between 10:00 AM and 6:00 PM, though participants may adjust to other 16-hour fasting windows. Participants will be evaluated before and after the intervention in terms of anthropometric measurements, biochemical parameters, and dietary habits. The study is being conducted at a private hospital in Bursa, Turkey, and is planned to be completed with a total of 40 participants (20 per group).

Conditions

Obesity & Overweight; Bariatric Surgery; Weight Regain; Weight Regain Post Bariatric Surgery; Time Restricted Feeding

Keywords

Time-Restricted Eating; Intermittent Fasting; Bariatric Surgery; Obesity; Weight Regain; Anthropometric Measurements; Nutritional Assessment

Outcome Measures

Primary Outcomes (8)

• Body Weight

  Change in body weight measured by digital scale

  Baseline and 6 weeks

• Body Mass Index (BMI)

  Change in BMI calculated as weight (kg) divided by height squared (m²)

  Baseline and 6 weeks

• Body Fat Mass

  Change in fat mass assessed by bioelectrical impedance analysis (Tanita MC-780 MA)

  Baseline and 6 weeks

• Muscle Mass

  Change in muscle mass assessed by bioelectrical impedance analysis (Tanita MC-780 MA)

  Baseline and 6 weeks

• Waist Circumference

  Change in waist circumference measured at 5 cm below the navel

  Baseline and 6 weeks

• Hip Circumference

  Change in hip circumference measured at the maximum point of gluteal muscles

  Baseline and 6 weeks

• Percentage of Excess Weight Loss (%EWL)

  Calculated as: \[(preoperative weight - postoperative weight) / (preoperative weight - ideal weight)\] × 100. Ideal body weight defined based on a BMI of 25 kg/m². Insufficient weight loss (IWL) defined as

  Baseline and 6 weeks

• Percentage of Total Weight Loss (%TWL)

  Calculated as: \[(preoperative weight - postoperative weight) / preoperative weight\] × 100. Used to assess overall weight loss outcomes in both bariatric and non-bariatric participants following the 6-week time-restricted eating intervention.

  Baseline and 6 weeks

Secondary Outcomes (2)

• Daily Energy Intake

  Baseline and 6 weeks

• Dietary Macronutrient Distribution

  Baseline and 6 weeks

Study Arms (2)

Arm 1: Adults with Obesity (Non-Bariatric)

ACTIVE COMPARATOR

Adults with obesity who have not undergone bariatric surgery. Will follow 16:8 TRE protocol for 6 weeks.

Behavioral: Time-Restricted Eating (16:8)

Arm 2: Adults with Obesity (Post-Bariatric)

EXPERIMENTAL

Adults with obesity who experienced insufficient weight loss or weight regain following bariatric surgery. Will follow 16:8 TRE protocol for 6 weeks.

Behavioral: Time-Restricted Eating (16:8)

Interventions

Time-Restricted Eating (16:8) BEHAVIORAL

Participants will follow a 16:8 time-restricted eating protocol for 6 weeks, limiting food intake to an 8-hour window (recommended 10:00 AM-6:00 PM, with flexibility to adjust). During the 16-hour fasting period, only water and non-caloric beverages (tea, coffee, soda) are permitted. Nutritional principles will be aligned with ASMBS guidelines.

Also known as: 16/8 Fasting

Arm 1: Adults with Obesity (Non-Bariatric); Arm 2: Adults with Obesity (Post-Bariatric)

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults aged 18-65 years with obesity who have not undergone bariatric surgery
• Adults aged 18-65 years with obesity who have undergone bariatric surgery and experienced insufficient weight loss (IWL) within 18 months post-surgery, -defined as %EWL \<50% at 18 months
• Adults aged 18-65 years with obesity who have undergone bariatric surgery and experienced weight regain (WR), defined as \>25% increase in %EWL from the lowest recorded weight

You may not qualify if:

• Pregnant or breastfeeding individuals
• Acute illness, active infection, or comorbid conditions limiting treatment efficacy and safety, including: cancer, type 1 diabetes, renal or hepatic failure, recent stroke or myocardial infarction, nephrolithiasis, drug or alcohol abuse, eating disorders, severe depression or other psychiatric disorders, inflammatory bowel disease (IBD), neoplasia, arrhythmic heart disease, heart failure, respiratory failure, or corticosteroid therapy
• Professional athletes

Sponsors & Collaborators

• Medipol University: lead

Study Sites (2)

Nev Sağlık Grubu

Bursa, Lütfen Seçiniz., 16940, Turkey (Türkiye)

RECRUITING

Nev Sağlık Grubu

Bursa, 16940, Turkey (Türkiye)

RECRUITING

MeSH Terms

Conditions

Obesity; Overweight; Intermittent Fasting

Condition Hierarchy (Ancestors)

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

Central Study Contacts

Seher Şen, Assistant Professor

CONTACT

+905393919700; seherdalli@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assist. Prof. Dr.

Study Record Dates

• First Submitted: June 23, 2026
• First Posted: June 29, 2026
• Study Start: July 12, 2025
• Primary Completion: June 1, 2026
• Study Completion: July 12, 2026
• Last Updated: June 29, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

TU (2)