Contribution of evening macronutrient intake to total caloric intake and body mass index

The goal of this study was to evaluate the relationship between sleep timing and macronutrient intake as an approach towards better understanding of how sleep and eating affect weight regulation. Fifty-two volunteers (25 women) completed 7 days of wrist actigraphy and food logs. Average sleepers (56%) were defined as having a midpoint of sleep <5:30 am and late sleepers (44%) were defined as having a midpoint of sleep >= 5:30 am. Data were analyzed using t-tests, correlations and regression. Late sleepers consumed a greater amount of protein fat and carbohydrates in the evening (defined as after 8:00 pm) but less fat in the 4 h before sleep. Total protein, protein, carbohydrate, and fat consumed after 8:00 pm, protein consumed within 4 h of sleep as well as the percentage of fat consumed after 8:00 were associated with higher BMI. The amount of protein and carbohydrates consumed within 4 h of sleep and the amount and percentage of carbohydrate and fat consumed after 8:00 pm were associated with greater total calories. In multivariate analyses controlling for age, gender, sleep timing and duration, protein consumed 4 h before sleep was associated with BMI; carbohydrates consumed after 8 pm, protein and carbohydrates consumed 4 h before sleep were associated with higher total calories. Results indicate that evening intake of macronutrients and intake before sleep are not synonymous, particularly among late sleepers. Eating in the evening or before sleep may predispose individuals to weight gain through higher total calories. (C) 2012 Elsevier Ltd. All rights reserved.