Plain language summary
Snacking is contributing to the obesity crisis, with obese individuals tending to favour high fat (HF) and/or high sugar snacks. It is unclear whether replacing the HF and/or high sugar snacks with a healthier alternative could improve obesity overcomes in young people. The aim of this small randomised, cross-over designed trial was to compare the effects high-protein (HP), HF afternoon snacks and no snacks (NoS) on measures including appetite, satiety and cognition. Thirty one healthy adolescents consumed HP, HF afternoon snacks or NoS in a random order over a three day period. Participants were observed in laboratory conditions for an eight hour period for each of the three day plus the fourth. Laboratory tests included functional magnetic renascence imaging (fMRI), food and mood questionnaires and cognitive tests. It was found that a HP snack improved appetite control and satiety compared to a HF snack or NoS. Additional a HP snack led to a reduction in the consumption of HF/high-sugar snacks later in the evening. No difference in cognition was detected between any of the groups.
Abstract
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.
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