Nighttime Consumption of Protein or Carbohydrate Improves Morning Resting Energy Expenditure in Active College-Aged Men
Amber W. Kinsey Medicine & Science in Sports & Exercise Volume 45, May 2013, Supplement 1 5S, p 218
Nighttime eating is an unexplored component of nutrient timing and no data exist regarding the satiating and metabolic effects of macronutrients consumed at night before sleep.
PURPOSE: To investigate whether whey protein (WP), casein protein (CP), carbohydrate (CHO), or a non-caloric placebo (PLA) consumed prior to sleep alters morning appetite and resting energy expenditure (REE) in active men.
METHODS: Eleven physically active men (age, 23.6 ± 3.1 years; body fat, 16.3 ± 8.2%) participated in this randomized, double blind, crossover study. A single dose of WP (30g), CP (30g), CHO (33g) or PLA was consumed 30 minutes prior to sleep and each trial was separated by 48-72 hours. The next morning (0500-0800), measurements of satiety, hunger, and desire to eat (visual analog scale) and REE (indirect calorimetry) were performed. After a 30 minute equilibration period, 60 minutes of REE in the supine position was measured. Ten-minute means (total of 5) over the final 50 minutes of measurement were analyzed. Outcome variables were oxygen consumption (VO2), REE, and respiratory quotient (RQ). Statistical analyses were conducted using a 4 x 5 (group x time) repeated measures ANOVA for metabolic variables and a one way ANOVA was used for changes in appetite markers. Group differences were examined by Tukey post-hoc analyses. Data are reported as mean ± SE.
RESULTS: There were no significant differences in appetite measures among or between groups. There were no group x time interactions for VO2, REE, and RQ; however there was a main effect for group. VO2 was significantly greater for WP (3.35 ± 0.03 ml/kg/min) and CP (3.30 ± 0.03 ml/kg/min, p < 0.0001) when compared to PLA (3.16 ± 0.03 ml/kg/min), but not CHO (3.25 ± 0.03 ml/kg/min).
Predicted REE was significantly greater after WP (1947 ± 16 kcal/d), CP (1941 ± 16 kcal/d) and CHO (1908 ± 16 kcal/d) compared to PLA (1843 ± 16 kcal/d, p < 0.0001). RQ was significantly lower after PLA (0.759 ± 0.003) compared to WP (0.773 ± 0.003) and CHO (0.773 ± 0.003, p < 0.0001) but not CP (0.764 ± 0.003). There were no significant differences between WP and CP in any metabolic measurements.
CONCLUSION: Nighttime consumption of WP, CP, or CHO, in close proximity to sleep, elicits favorable effects on next morning metabolism when compared to a non-caloric PLA in active
young men.