Soy milk induces higher postprandial satiety than cow’s milk: a cross-overexperiment in healthy normal female adults

The differential impact of plant-based versus animal-based proteins on satiety has been a topic of interest in recent years. This paper aimed to compare the effects of soy milk, a plant-based protein source, and cow's milk, an animal-based protein source, on short-term satiety. A crossover, single-blinded study was conducted involving twenty-eight healthy Indonesian females (BMI between 18 and 25 kg/m2 , aged 19 to 21 years). Both test diets consisted of 200 mL of either soy milk (SM) or cow's milk (CM), both isovolumetric, isocaloric, and isomacronutrient (220 kcal, protein 20% En). Participants fasted overnight before diet administration and Visual Analogue Scale (VAS) questionnaires were used to assess perceived satiety. After 3 hrs of milk ingestion, an ad-libitum lunch was provided to evaluate prospective food consumption (PFC). Analysis of variance (ANOVA) repeated measures and paired T-tests or Wilcoxon were employed to compare perceived satiety and PFC. No significant differences were observed in all VAS scores. However, the area under the curve score for perceived PFC was significantly lower in the SM group (SM = 129.7±7 mm*mins; CM = 138.9±8 mm*mins). The PFC was slightly lower in the SM group than in the CM group, but the difference was not significant (337.9±16.5 kcal vs. 367±26.71 kcal). Only the SM group showed a more sustained fullness which lasted until t = 180. This present study suggested that compared to CM, SM has a higher short-term satiety effect. The higher fiber content in SM, which is known to increase satiety, might be a factor that contributed to this present finding. This evidence provided crucial information regarding the potential of SM to prevent weight gain by promoting short-term satiety sensation. The factor that may contribute to this finding could be the higher fiber content in SM, which has been shown to promote satiety and reduce insulin response. Future studies should investigate this underlying mechanism by incorporating fiber content analysis and exploring the relationship between fiber intake, insulin response, and satiety. Long-term studies are also required to determine the sustained effects of soy milk on weight management and weight loss.