Effects of Protein Source and Quantity on Appetite Control, Satiety and Subsequent Food Intake in Healthy Adults

Abstract

Objectives: To examine whether consumption of breakfast preloads varying in protein source and quantity affect measures of appetite, satiety and subsequent energy intake in healthy adults. Methods: Thirty-seven healthy adults (Age: 26 ± 4; BMI: 23 ± 2) participated in this randomized crossover design study. On 3 consecutive days, participants consumed 325 kcal preload breakfast yogurts, varying in protein quality (Whey vs. Pea) and quantity (20, 30, 40 g) vs. an isocaloric carbohydrate preload (Control). On day 4, participants completed a 5-hr in clinic testing day. At baseline time-15 min, questionnaires assessing hunger, fullness, desire to eat, prospective food consumption, and eating initiation, were completed. At time 0 min, the respective preload was provided, and palatability assessed. At time 15 min, after consumption, similar questionnaires were completed every 30 min during the 4-h postprandial period followed by an ad libitum pizza lunch. There was a 3-7 day washout period between testing days. To assess main effects of protein source, paired sample t-tests of incremental area under the curve (iAUC) were computed for 20g Pea vs. 20g Whey preloads on 4-h hunger, fullness, desire to eat, prospective food consumption, eating initiation and lunch energy intake. To assess main effects of protein quantity, repeated measures ANOVA was computed between control and pea protein preloads of 20g, 30g, and 40g on 4-h hunger, fullness, desire to eat, and prospective food consumption niAUC, eating initiation, and lunch energy intake. P < 0.05 was considered statistically significant. Statistical analyses were performed using The R Foundation (R; version 4.0.3). Results: No main effects of protein source or quantities were detected for 4-h postprandial hunger, fullness, desire to eat, and prospective food consumption niAUC. On average, participants requested to eat again 2-h after breakfast (134 ± 12 min) and consumed on average 830 ± 10 kcals at lunch with no differences between protein sources or quantities. Conclusions: In the context of an acute feeding study, no differences in postprandial appetite, satiety, and subsequent food intake were detected when comparing protein preloads varying in source and quantity. These data suggest that 20 g pea protein is sufficient to elicit satiety effects and can be used as a plant-based alternative for whey protein.