Sex and race differences in caloric intake during sleep restriction in healthy adults.

BACKGROUND

Evidence indicates that men and African Americans may be more susceptible to weight gain resulting from sleep loss than women and whites, respectively. Increased daily caloric intake is a major behavioral mechanism that underlies the relation between sleep loss and weight gain.

OBJECTIVE

We sought to assess sex and race differences in caloric intake, macronutrient intake, and meal timing during sleep restriction.

DESIGN

Forty-four healthy adults aged 21-50 y (mean ± SD: 32.7 ± 8.7 y; n = 21 women, n = 16 whites) completed an in-laboratory protocol that included 2 consecutive baseline nights [10 or 12 h time in bed (TIB)/night; 2200-0800 or 2200-1000] followed by 5 consecutive sleep-restriction nights (4 h TIB/night; 0400-0800). Caloric intake and meal-timing data were collected during the 2 d after baseline sleep and the first 3 d after sleep restriction.

RESULTS

During sleep restriction, subjects increased daily caloric intake (P < 0.001) and fat intake (P = 0.024), including obtaining more calories from condiments, desserts, and salty snacks (Ps < 0.05) and consumed 532.6 ± 295.6 cal during late-night hours (2200-0359). Relative to women, men consumed more daily calories during baseline and sleep restriction, exhibited a greater increase in caloric intake during sleep restriction (d = 0.62), and consumed a higher percentage of daily calories during late-night hours (d = 0.78, Ps < 0.05). African Americans and whites did not significantly differ in daily caloric intake, increased caloric intake during sleep restriction, or meal timing. However, African Americans consumed more carbohydrates, less protein, and more caffeine-free soda and juice than whites did during the study (Ps < 0.05).

CONCLUSIONS

Men may be more susceptible to weight gain during sleep loss than women due to a larger increase in daily caloric intake, particularly during late-night hours. These findings are relevant to the promotion of public health awareness by highlighting nutritional risk factors and modifiable behaviors for weight gain related to sleep-wake timing.