Background/objectives: There is increasing evidence to support that a high-protein diet may promote weight loss and prevent weight (re)gain better than a low-protein diet, and that the effect is due to higher diet-induced thermogenesis (DIT) and increased satiety. However, data on the effect of different types of protein are limited. In the present study we compare the effect of whey, casein and milk on DIT and satiety.
Subjects/methods: Seventeen slightly overweight (29 ± 4 kg/m(2)) male subjects completed the study. The study had a randomized, crossover design, where the effect on 4 h postprandial energy expenditure (EE), substrate oxidation and subjective appetite sensation of three isocaloric test meals containing either a whey drink, a casein drink or skim milk was examined. Energy intake (EI) at a subsequent ad libitum lunch was also measured.
Results: There was no significant effect on subjective appetite sensation, but EI at lunch was lower after the milk test meal than after the casein (9%; P=0.0260) and the whey (9%; P=0.0258) test meals. Postprandial lipid oxidation was significantly higher after the casein test meal compared with the whey test meal (P=0.0147) when adjusted for baseline values. There was no significant difference in effect on EE, protein oxidation or carbohydrate oxidation.
Conclusions: Milk reduced subsequent EI more than isocaloric drinks containing only whey or casein. A small but significant increase in lipid oxidation was seen after casein compared with whey.