This randomized clinical trial tested whether shifting the timing of the evening meal earlier improves weight loss and cardiometabolic outcomes during a structured weight-loss program. Eighty-two women with overweight or obesity (BMI 27–35; ages 18–45) who were habitual late-evening eaters were assigned to one of two dinner schedules for 12 weeks: an early evening meal (around 19:00–19:30) or a late evening meal (around 22:30–23:00). Both groups followed the same energy-restricted diet approach and received the same lifestyle support through a clinic-based program, so the main difference between groups was dinner timing rather than the overall diet content or coaching intensity.

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Participants received individualized meal plans designed to create a meaningful daily energy deficit and target approximately 7–10% weight loss across the 12-week period. The program also encouraged gradual increases in physical activity, aiming for regular moderate activity most days of the week. Participants attended frequent clinic visits and weekly check-ins to support adherence. Dinner timing was tracked using logs, dietary intake was recorded at baseline and follow-up time points, and fasting blood samples were collected at baseline and week 12 to assess lipid markers and glucose/insulin-related measures. Insulin resistance was estimated using HOMA-IR.

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Both groups lost weight, but earlier dinner timing produced significantly greater results. Over 12 weeks, the early-dinner group achieved a larger mean reduction in body weight (about 6.7 kg versus 4.8 kg), along with greater reductions in BMI and waist circumference. Earlier dinner timing also led to more favorable changes in several cardiometabolic measures. Total cholesterol and triglycerides decreased more in the early-dinner group, and insulin-related outcomes improved more strongly, including a larger reduction in fasting insulin and HOMA-IR, suggesting greater improvements in insulin sensitivity.

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A key point is that these differences were not explained by major differences in reported calorie intake or macronutrient intake, which were broadly similar between groups across the intervention. Physical activity, measured using step counts at key points, increased over time in both groups without meaningful differences between groups. Reported compliance with the assigned dinner time was also high in both arms. Taken together, this supports the interpretation that meal timing—specifically avoiding very late dinners—may influence weight-loss and metabolic outcomes beyond calorie targets alone, at least in the context of a structured program.

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The authors note limitations that matter for interpretation, including the free-living design (which relies on self-report for some adherence measures), the relatively short duration, and the fact that the study included only women in a specific age range. Even so, the results support a practical takeaway for weight-loss programs: shifting the evening meal earlier may be a simple behavioral lever that improves weight loss and insulin resistance outcomes.