Background: Until recently, consuming nutrients close to sleep was believed to have negative impacts on body composition and overall health. However, recent work from our laboratory and others has demonstrated that a low calorie snack, high in protein may be beneficial for facilitating weight loss in overweight and obese adults, increasing overnight muscle protein synthesis in both young and old men, increasing morning metabolism in young men and decreasing morning hunger in overweight and obese women. To date, no studies have investigated the impact of casein intake before sleep on appetite the following morning in overweight and obese men. Purpose: The present study investigated whether casein (CAS) protein consumed within 30 min of sleep could acutely alter morning appetite in overweight or obese men the next morning when compared to a non-caloric placebo (PLA). Methods: Twelve overweight and obese men completed this randomized, crossover, double blind and placebo-controlled study. Subjects came to the laboratory on three occasions: baseline, and in the morning following CAS and placebo (PLA). Within 30 min of sleep, CAS or PLA was consumed. The next morning (6-8 hours later), subjective appetite (visual analog scales for hunger, satiety, and desire to eat) and ghrelin levels (blood samples) were measured. Results: There were no significant differences in next morning hunger (BAS, 35 ± 6; CAS, 49 ± 6; PLA, 47 ± 6 mm, p = 0.21), satiety (BAS, 36 ± 6; CAS, 36 ± 4, PLA, 39 ± 5 mm; p = 0.89), or desire to eat (BAS, 38 ± 6; CAS, 62 ± 8; PLA, 55 ± 5 mm; p = 0.06). Additionally, there were no significant differences in next morning acyl ghrelin (BAS, 54.8 ± 15.7; CAS, 54.3 ± 10; PLA, 61.3 ± 15 pg/ml, p = 0.93), desacyl ghrelin (BAS, 46.4 ± 9; CAS, 43.4 ± 6.9; PLA, 45 ± 9.9 pg/ml; p = 0.97) or ghrelin ratio (BAS, 1.3 ± 0.4; CAS, 1.6 ± 0.4; PLA, 2.3 ± 1.0, p = 0.63). Conclusion: The results of the present study reveal that CAS can be consumed within 30 minutes of sleep without negatively affecting next morning appetite or insulin levels in overweight and obese men. Long-term studies are needed to evaluate the effects of chronic protein consumption before sleep on body composition and appetite.
