Low-dose whey protein-enriched water beverages alter satiety in a study of overweight women

Aim: To determine the effect of low-dose whey protein-enriched water beverages on postprandial satiety and energy intake (EI). Methods: Fifty overweight and mildly obese women were given 500 mL water-based beverages on 4 different occasions in a double blind, cross-over study. The beverages were reasonably matched for colour, flavour, sweetness and contained 0% (water control, 0 g, 8 kJ), 1% (5 g, 93 kJ), 2% (10 g, 178 kJ) and 4% (20 g, 348 kJ) whey protein by weight (ClearProtein8855™). Following a standard evening meal and breakfast, beverages were consumed 120 min before an ad libitum lunch at which EI was measured. Feelings associated with hunger and fullness were also measured using visual analogue scales (VAS). Results: 46 participants completed all 4 beverage conditions. There was a significant effect of beverage preload on hunger (beverage × time; P = 0.0074), where each of the 1%, 2% and 4% w/w protein beverages decreased hunger compared to the water control ( P < 0.05). Suppression of hunger was also maintained for longer following the protein beverages (Friedman test, P = 0.013). Fullness (beverage × time; P = 0.0020) and satisfaction (beverage × time; P = 0.0356) were both increased by the 1% and 4% protein beverages ( P < 0.05). EI at lunch decreased by up to 8 percent (control vs 4% protein, delta = −247 kJ, Tukey's post hoc, P > 0.05) when escalating protein doses were added to the water preload (water control, 3028 kJ; 1%, 3080 kJ; 2%, 2924 kJ; 4%, 2781 kJ), only partial compensation for the added energy. Conclusions: These low-dose, whey protein-enriched water beverages significantly altered short term postprandial satiety, however the effect was not sufficient to impact on food intake when assessed 2 h after consumption.