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

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).