Effects of Evening Meal Timing on Weight Loss: A Pilot Open-Labelled Randomized Clinical Trial

Background & Objective:  Recent studies have shown the effect of meal timing on weight-loss diet success with controversial results. The current study evaluated the effect of evening meal timing on weight and body mass index (BMI) in overweight/obese subjects who were on a standard weight-loss diet. Materials & Methods:  A total of 70 obese/overweight employees of Ahvaz Jundishapur University of Medical Sciences took part in this randomized clinical trial (RCT). Participants were randomly assigned into a limited meal timing weight-loss (LMTWL) group with the last meal before 06:00 PM and a non-limited meal timing weight-loss (NLMTWL) group with the last meal before 12:00 AM. All participants followed a standard weight-loss diet as follows: 53 carbohydrate 30 fat and 17 protein. Weight and body mass index was measured at the run-in-period (2 weeks), baseline and the end of four weeks. Independent sample T-test was used to compare parametric continuous variables between the two groups. Results:  Of participants, 60 were female. However, there was no significant difference between the two groups based on sex. Also, age, height, physical activity level, BMI and energy intake was similar between the two groups. There were no differences in LMTWL and NLMTWL groups based on weight (P=0.89) and BMI (P=0.91) before and after four weeks of the intervention. Conclusion:  Meal timing did not influence the amount of weight lost by overweight/obese subjects on a weight-loss diet. However, more RCTs with larger samples and longer follow-up durations (with a focus on nutrient intake, circadian clock patterns, and the interaction between genotype and chronotype) are needed to confirm this finding.