Meal Frequency and Timing on Metabolic Health in Patients With Type 2 Diabetes

The Effects of Meal Frequency and Timing on Lipid Profile, Glycemic Control, and Body Composition in Individuals With Type 2 Diabetes Mellitus: A 12-Week Randomized Controlled Trial

The goal of this clinical trial is to learn if changing when and how often people eat works to improve health in adults with Type 2 diabetes. The main questions it aims to answer are:

How do these eating patterns change body weight and body fat?

Does changing meal timing and frequency lower blood sugar levels (HbA1c) over 12 weeks?

Does it lower blood fat levels, such as cholesterol and triglycerides?

Researchers will compare three groups to see which eating pattern works best:

Standard Group: Participants eat 3 main meals and 3 snacks (6 times total) each day with a calorie limit.

3-Meal Group: Participants eat only 3 main meals each day with a calorie limit.

Time-Restricted Group: Participants eat all their daily food within an 8-hour window (from 12:00 to 20:00) without a calorie limit.

Participants will:

Follow their assigned eating plan for 12 weeks.

Visit the clinic once every month for checkups and body measurements.

Give blood samples at the start and end of the study for laboratory tests.

Record the food they eat and their physical activity levels.

Study Overview

• Status: Completed
• Conditions: Type 2 Diabetes; Obesity and Overweight
• Intervention / Treatment: Other: Control Arm - standard of care; Other: Three Meal Group; Other: Time-restricted eating

Detailed Description

This randomized controlled trial investigates the impact of meal frequency and timing on the body composition and metabolic profile of individuals diagnosed with Type 2 Diabetes Mellitus (T2DM). While medical management is a cornerstone of T2DM treatment, dietary patterns, specifically the distribution of meals and fasting windows, may significantly modulate glycemic variability and lipid metabolism.

Methodology and Rationale:

The study follows a three-arm parallel design for 12 weeks. Participants are randomized into Control (6 meals), 3-Meal, or Time-Restricted Eating (TRE) groups using Random Allocation Software.

Energy Expenditure Calculation: For the Control and 3-Meal groups, daily energy requirements are calculated using the Mifflin-St Jeor equation. A 500 kcal/day deficit is applied, ensuring that total energy intake does not fall below the Basal Metabolic Rate (BMR).

Time-Restricted Eating (TRE) Protocol: The TRE group follows an 8-hour eating window (12:00-20:00) consisting of 2 main meals and 2 snacks. Unlike the other groups, no explicit calorie restriction is mandated for the TRE arm, allowing the researchers to observe the spontaneous effects of a restricted feeding window on metabolic parameters.

Dietary Composition: All groups are instructed to follow standard medical nutrition therapy for T2DM, emphasizing high fiber, low saturated fat, and high-quality protein sources.

Sample Size and Statistical Power:

Sample size was estimated based on body weight changes reported in a 12-week time-restricted feeding RCT in overweight adults with type 2 diabetes (Che et al., 2021), which yielded a Cohen's f of 0.40 for between-group differences in body weight. Using one-way ANOVA with α = 0.05 and 80% power (G*Power 3.1), a minimum of 22 participants per group was required for the primary outcome. To also achieve adequate power for the secondary outcome of HbA1c (Cohen's f = 0.35, derived from the same reference), a minimum of 29 participants per group was indicated. Accounting for an anticipated 20% dropout rate, 48 participants per group (144 total) were enrolled

Data Collection and Follow-up:

Anthropometry: Body composition is analyzed monthly using Bioelectrical Impedance Analysis (BIA - Tanita MC 580).

Biochemistry: HbA1c, Fasting Plasma Glucose, Lipid Profile (Total-C, LDL-C, HDL-C, Triglycerides), and Albumin/Creatinine Ratio (UACR) are recorded at baseline and at the end of the 12th week.

Dietary Compliance: Weekly phone calls are conducted to monitor adherence, meal skipping, and protocol deviations. 24-hour dietary recalls are collected at baseline and at the 12th week to verify nutrient intake using professional nutrition software (BeBİS 9.0).

• Study Type: Interventional
• Enrollment (Actual): 144
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Konyaalti
    • Antalya, Konyaalti, Turkey (Türkiye), 07070
      • Akdeniz University Faculty of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Diagnosed with Type 2 Diabetes Mellitus (T2DM) for at least 6 months.
• Aged between 18 and 65 years.
• Residing in Antalya, Turkey (to ensure regular follow-up visits).
• Able and willing to provide informed consent.
• Willing to comply with the assigned dietary protocol and follow-up measurements for 12 weeks.

Exclusion Criteria:

• Diagnosis of Type 1 Diabetes Mellitus or other specific types of diabetes.
• Current pregnancy or breastfeeding.
• Working in night shifts or irregular schedules (due to interference with Time-Restricted Eating protocols).
• Having a history of major cardiovascular events (e.g., myocardial infarction, stroke) within the last 6 months.
• Severe renal or hepatic impairment (e.g., Stage 4 or 5 Chronic Kidney Disease).
• Active malignancy or other chronic diseases that may significantly affect nutritional status.
• Significant weight change (more than 5% of body weight) within the last 3 months prior to the study.
• Use of medications that may significantly affect body weight or metabolism other than standard diabetes medications (e.g., systemic corticosteroids).
• History of major gastrointestinal surgery that affects nutrient absorption.
• Severe psychiatric disorders that may limit the ability to follow the study instructions.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Control; 3 main meals and 3 snacks with a 500 kcal/day deficit based on Mifflin-St Jeor equation.	Other: Control Arm - standard of care; Control Group: 3 main meals and 3 snacks approach routinely applied in the treatment of T2DM (500 kcal restricted from daily energy requirement)
Active Comparator: 3-meal group; 3 main meals only with a 500 kcal/day deficit based on Mifflin-St Jeor equation.	Other: Three Meal Group; 3M: Diet with 3 main meals restricted by 500 kcal from the daily energy requirement
Active Comparator: TRF; Ad-libitum feeding within an 8-hour window (12:00-20:00) with 2 main meals and 2 snacks.	Other: Time-restricted eating; Ad-libitum feeding within an 8-hour window (12:00-20:00) with 2 main meals and 2 snacks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Body Weight	The primary goal is to evaluate the effect of meal frequency and timing on total body weight. This parameter was used to determine the study's sample size, based on a target of a 5% weight reduction. Measurement is performed in kilograms (kg).	From enrollment to the end of treatment at 12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycated Hemoglobin	Evaluation of long-term glycemic control, measured as the percentage (%) of glycated hemoglobin in the blood.	Change from baseline to Week 12.
Fasting Plasma Glucose	Concentration of glucose in the blood after an overnight fast, measured in mg/dL.	Change from baseline to Week 12.
Waist Circumference	Measurement of abdominal obesity in centimeters (cm).	Change from baseline to Week 12.
Urinary Albumin/Creatinine Ratio	Screening for renal health, measured in mg/g creatinine.	Change from baseline to Week 12.
Triglyceride	Concentration of triglycerides in the blood after an overnight fast, measured in mg/dL.	Week 0 and Week 12
LDL-C	Concentration of low-density lipoprotein (LDL) cholesterol in the blood after an overnight fast, measured in mg/dL.	Week 0 and Week 12
HDL-C	Concentration of high-density lipoprotein (HDL) cholesterol in the blood after an overnight fast, measured in mg/dL.	Week 0 and Week 12
Total Cholesterol	Concentration of total cholesterol in the blood after an overnight fast, measured in mg/dL.	Week 0 and week 12
Body Mass Index	Body mass index calculated from height and weight, measured in kg/m²	Week 0 and Week 12
Body Fat Percentage	Percentage of total body fat mass assessed via bioelectrical impedance analysis (BIA), measured in %.	Week 0 and week 12
Skeletal Muscle Mass	Total skeletal muscle mass assessed via bioelectrical impedance analysis (BIA), measured in kg.	Week 0 and week 12
Fat Mass Index	Fat mass indexed to height squared, assessed via bioelectrical impedance analysis (BIA), measured in kg/m².	Week 0 and week 12
Fat Free Mass Index	Fat-free mass indexed to height squared, assessed via bioelectrical impedance analysis (BIA), measured in kg/m²	Week 0 and week 12

Collaborators and Investigators

• Sponsor: Akdeniz University
• Investigators: Principal Investigator: Hülya KAMARLI ALTUN, PhD, Associate Professor, Akdeniz University

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2024
• Primary Completion (Actual): November 15, 2024
• Study Completion (Actual): November 30, 2024

Study Registration Dates

• First Submitted: June 17, 2026
• First Submitted That Met QC Criteria: June 29, 2026
• First Posted (Actual): June 30, 2026

Study Record Updates

• Last Update Posted (Actual): June 30, 2026
• Last Update Submitted That Met QC Criteria: June 29, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: obesity; meal frequency; type 2 diabetes; weight loss; intermittent fasting; energy restriction; time-restricted feeding
• Additional Relevant MeSH Terms: Endocrine System Diseases; Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Body Weight Changes; Glucose Metabolism Disorders; Diabetes Mellitus; Pathological Conditions, Signs and Symptoms; Behavior; Nutritional and Metabolic Diseases; Signs and Symptoms; Feeding Behavior; Fasting; Overweight; Obesity; Weight Loss; Diabetes Mellitus, Type 2; Intermittent Fasting
• Other Study ID Numbers: TBAEK-121 (Akdeniz University)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data collected during the trial, including biochemical and anthropometric measurements, will not be shared publicly to maintain participant confidentiality and adhere to the Personal Data Protection Law. The data are strictly confidential and belong to the primary research institution. Results will be disseminated through peer-reviewed publications and conference presentations in aggregate form.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No