Consuming High-Protein Soy Snacks Affects Appetite Control, Satiety, and Diet Quality in Young People and Influences Select Aspects of Mood and Cognition.

BACKGROUND

Data concerning the effects of afternoon snacking on ingestive behavior, mood, and cognition are limited.

OBJECTIVE

The purpose of this study was to compare 1088 kJ of high-protein (HP) or high-fat (HF) afternoon snacks vs. no snacking on appetite, food intake, mood, and cognition in adolescents.

METHODS

Thirty-one healthy adolescents (age: 17 ± 1 y) consumed the following afternoon snacks (in randomized order) for 3 d: HP snack (26 g of protein/6 g of fat per 27 g of carbohydrates), HF snack (4 g of protein/12 g of fat per 32 g of carbohydrates), and no snack (NoS). On day 4 of each treatment, the participants completed an 8-h testing day containing pre- and postsnack appetite questionnaires, food cue-stimulated functional MRI brain scans, mood, cognitive function, and eating initiation. Ad libitum dinner and evening snacks were provided and assessed.

RESULTS

HP, but not HF, delayed eating initiation vs. NoS (P < 0.05). Both snacks reduced appetite vs. NoS (P < 0.001) with HP eliciting greater reductions than HF (P < 0.05). Only HF led to reductions in corticolimbic activation in brain regions controlling food motivation/reward vs. NoS (P < 0.01). Although no treatment differences in daily energy intake were detected, HP led to greater protein consumption than NoS (P < 0.05) and greater protein and lower fat consumption than HF (both, P < 0.05). HP led to fewer HF/high-sugar evening snacks than NoS (P < 0.01) and HF (P = 0.09). Although no treatment effects were detected for mood and cognition, HP tended to reduce confusion-bewilderment (P = 0.07) and increase cognitive flexibility (P = 0.09), whereas NoS reduced tension-anxiety (P < 0.05) and vigor-activity (P < 0.05).

CONCLUSION

Afternoon snacking, particularly on HP soy foods, improves appetite, satiety, and diet quality in adolescents, while beneficially influencing aspects of mood and cognition. This trial was registered at clinicaltrials.gov as NCT01781286.