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

Background & aims: 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). Methods: 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. Results: Both at the level of 10 and 25 En% from protein, El at lunch was similar to 20% lower after an alpha-lactaibumin 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 (similar to 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). Conclusions: Different proteins (alpha-lactalbumin, gelatin, gelatin + TRIP) that are similar to 40% more satiating than other proteins (casein, soy, whey, whey-GMP) induce a related similar to 20% reduction of subsequent energy intake. (C) 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.