Effects of protein quality on appetite and energy metabolism in normal weight subjects.

OBJECTIVE The purpose of this study was to compare the effects of consumption of different protein sources on food intake and energy expenditure in normal weight subjects. SUBJECTS AND METHODS Breakfast preparations (casein, soy protein, whey protein or control) were ingested during seven consecutive days. Appetite, food intake, and energy expenditure were assessed. RESULTS Casein consumption led to a lower energy intake than whey protein. There was lower energy intake on day 7 than on day 1 of the casein session. Soy protein preparations resulted in higher diet induced thermogenesis (DIT) than in control preparations. The respiratory quotient (RQ) obtained in the whey protein session was lower than the control and soy protein sessions. CONCLUSION These results suggest that the consumption of different protein types leads to distinct effects on satiety (casein), DIT (soy protein), and/or RQ (whey protein).