Effects of whey protein and its two major protein components on satiety and food intake in normal-weight women

Protein is the most satiating macronutrient and is source dependent, with whey protein thought to be particularly satiating. The purported satiating effect of whey protein may be due to the unique mixture of proteins in whey or to the major constituent individual proteins (beta-lactoglobulin and a-lactalbumin). The objective of the study was to compare the effects of isoenergetic (similar to 2100 kJ, similar to 500 kcal) preload meals enriched (similar to 50 g protein) with either whey protein isolate (WP), beta-lactoglobulin (BL) isolate or alpha-lactalbumin (AL) isolate, on food intake at an ad libitum test meal 120 min later and subjective ratings of appetite (hunger, desire to eat, prospective food consumption and fullness) using visual analogue scales (VAS). Twenty adult normal-weight women (mean age 24.2 +/- 0.8 years; mean BMI 22.7 +/- 0.4 kg/m(2)) participated in the study which used a single-blind completely randomised block design, where each subject consumed each of the three preload meals. Energy intake at the ad libitum test meal and total energy intakes (preload + test meal) did not differ between the three preload meals (p > 0.05). There were no significant differences observed for the VAS scores and net incremental area under the curve (net iAUC) during the 120 min following consumption of the three preload meals for subjective ratings of appetite (p > 0.05). The findings show that the satiating effect of whey protein was similar to that of BL or AL individually and suggest that the major whey protein components BL and AL do not mediate the satiating effect of whey protein.