Timing of energy intake during the day is associated with the risk of obesity in adults

Background: The timing of energy intake is a modifiable behaviour that may influence energy regulation and the risk of obesity. We examined the associations of energy intake in the morning, midday and evening with body mass index (BMI) (n = 239).

Methods: Cross-sectional analyses were performed using data from the University of California, Los Angeles Energetics Study. Energy intake was assessed using three 24-h dietary recalls and stratified by time-of-day: morning (00.00 h to 11.00 h), midday (11.00 h to 17.00 h) and evening (17.00 h to 00.00 h). Sensitivity analysis was conducted among 'true-reporters', whose self-reported energy intake was ±25% of total energy expenditure measured by doubly-labelled water (n = 99). Logistic regression models were performed adjusting for age, sex, race, education, total daily energy intake and physical activity.

Results: Energy intake in the morning was not associated with BMI. Participants who consumed ≥33% (versus <33%) of their daily energy intake at 12.00 h were (nonsignificantly) less likely to be overweight/obese [odds ratio (OR) = 0.68; 95% confidence interval (CI) = 0.37-1.24] and this association was stronger and statistically significant among true-reporters (OR = 0.34; 95% CI = 0.12-0.95). Those who consumed ≥33% of daily energy intake in the evening were two-fold more likely overweight/obese (OR = 2.00; 95% CI = 1.03-3.89), although this association was not significant among true-reporters (OR = 2.10; 95% CI = 0.60-7.29).

Conclusions: These data indicate that eating more of the day's total energy intake at midday is associated with a lower risk of being overweight/obese, whereas consuming more in the evening is associated with a higher risk. Randomised trials are needed to test whether shifting energy intake earlier in the day could have a regulatory effect with respect to reducing intake in the evening, thereby promoting weight loss and maintenance.