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

SummaryBackground & aimsDietary 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).MethodsTwenty-four healthy subjects (mean ± SEM BMI: 24.8 ± 0.5 kg/m2; 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.ResultsBoth at the level of 10 and 25 En% from protein, EI at lunch was ∼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 (∼40%, p < 0.05) between types of protein.Differences in EI were a function of differences in appetite ratings (R2 = 0.4, p < 0.001).ConclusionsDifferent proteins (alpha-lactalbumin, gelatin, gelatin + TRP) that are ∼40% more satiating than other proteins (casein, soy, whey, whey-GMP) induce a related ∼20% reduction of subsequent energy intake.