Meal Frequency and Timing Are Associated with Changes in Body Mass Index in Adventist Health Study 2

Background: Scientific evidence for the optimal number, timing, and size of meals is lacking.Objective: We investigated the relation between meal frequency and timing and changes in body mass index (BMI) in the Adventist Health Study 2 (AHS-2), a relatively healthy North American cohort.Methods: The analysis used data from 50,660 adult members aged ≥30 y of Seventh-day Adventist churches in the United States and Canada (mean ± SD follow-up: 7.42 ± 1.23 y). The number of meals per day, length of overnight fast, consumption of breakfast, and timing of the largest meal were exposure variables. The primary outcome was change in BMI per year. Linear regression analyses (stratified on baseline BMI) were adjusted for important demographic and lifestyle factors.Results: Subjects who ate 1 or 2 meals/d had a reduction in BMI per year (in kg · m^-2 · y^-1) (-0.035; 95% CI: -0.065, -0.004 and -0.029; 95% CI: -0.041, -0.017, respectively) compared with those who ate 3 meals/d. On the other hand, eating >3 meals/d (snacking) was associated with a relative increase in BMI (P < 0.001). Correspondingly, the BMI of subjects who had a long overnight fast (≥18 h) decreased compared with those who had a medium overnight fast (12-17 h) (P < 0.001). Breakfast eaters (-0.029; 95% CI: -0.047, -0.012; P < 0.001) experienced a decreased BMI compared with breakfast skippers. Relative to subjects who ate their largest meal at dinner, those who consumed breakfast as the largest meal experienced a significant decrease in BMI (-0.038; 95% CI: -0.048, -0.028), and those who consumed a big lunch experienced a smaller but still significant decrease in BMI than did those who ate their largest meal at dinner.Conclusions: Our results suggest that in relatively healthy adults, eating less frequently, no snacking, consuming breakfast, and eating the largest meal in the morning may be effective methods for preventing long-term weight gain. Eating breakfast and lunch 5-6 h apart and making the overnight fast last 18-19 h may be a useful practical strategy.