A breakfast with alpha-lactalbumin, gelatin, or gelatin + TRP lowers energy intake at lunch compared with a breakfast with casein, soy, whey, or whey-GMP

Abstract

Dietary protein plays a role in body weight regulation, partly due to its effects on satiety. The objective was to compare the effects of casein-, soy-, whey-, whey without glycomacropeptide (GMP)-, alpha-lactalbumin-, gelatin-, or gelatin with tryptophan (TRP)-protein breakfasts at two concentrations on subsequent satiety and energy intake (EI). Twenty-four healthy subjects (mean+/-SEM BMI: 24.8+/-0.5 kg/m(2); age: 25+/-2 years) received a breakfast; a custard with casein, soy, whey, whey-GMP, alpha-lactalbumin, gelatin, or gelatin+TRP as protein source with either 10/55/35 (normal) or 25/55/20 (high) En% protein/carbohydrate/fat in a randomized, single-blind design. At the precedingly determined time point for lunch, 180 min, subjects were offered an ad lib lunch. Appetite profile (Visual Analogue Scales, VAS) and EI were determined. Both at the level of 10 and 25 En% from protein, EI at lunch was approximately 20% lower after an alpha-lactalbumin or gelatin (+TRP) breakfast (2.5+/-0.2 MJ) compared with after a casein, soy, or whey-GMP breakfast (3.2+/-0.3 MJ, p<0.05). Appetite ratings at 180 min differed 15-25 mm (approximately 40%, p<0.05) between types of protein. Differences in EI were a function of differences in appetite ratings (R(2)=0.4, p<0.001). Different proteins (alpha-lactalbumin, gelatin, gelatin+TRP) that are approximately 40% more satiating than other proteins (casein, soy, whey, whey-GMP) induce a related approximately 20% reduction of subsequent energy intake.