Acute metabolic effects of consuming either whey protein concentrate or hydrolysate versus carbohydrate in healthy young men
The acute metabolic responses to consuming isocaloric drinks containing either whey protein concentrate (WPC), whey protein hydrolysate (WPH), or carbohydrate placebo (CHO) were examined. In a single-blind, randomized, crossover design, 14 healthy young men consumed each of the treatments and had their resting energy expenditure (REE) and respiratory exchange ratio (RER) assessed by indirect calorimetry over a 3-hr postprandial period. Values were compared to a pretreatment, fasting baseline measurement using repeated-measures ANOVA. WPH and WPC significantly (p < .05) elevated REE versus CHO, and WPC elevated REE greater than WPH at 120 min. WPH significantly (p < .05) lowered RER compared to CHO and WPC at 90 min. Both proteins increased REE versus isocaloric CHO, indicating a higher thermic effect of food. WPH, but not WPC, influenced substrate utilization with a shift favoring lipid metabolism versus CHO, which may help explain previous findings of fat loss with WPH, but not WPC.