Metabolic, endocrine and appetite-related responses to acute and daily milk snack consumption in healthy, adolescent males

Comprising of two experiments, this study assessed the metabolic, endocrine and appetite-related responses to acute and chronic milk consumption in adolescent males (15-18 y). Eleven adolescents [mean ± SD age: 16.5 ± 0.9 y; BMI: 23.3 ± 3.3 kg/m2] participated in the acute experiment and completed two laboratory visits (milk vs. fruit-juice) in a randomized crossover design, separated by 7-d. Seventeen adolescents [age: 16.1 ± 0.9 y; BMI: 21.8 ± 3.7 kg/m2] completed the chronic experiment. For the chronic experiment, a parallel design with two groups was used. Participants were randomly allocated and consumed milk (n = 9) or fruit-juice (n = 8) for 28-d, completing laboratory visits on the first (baseline, day-0) and last day (follow-up, day-28) of the intervention phase. On laboratory visits (for both experiments), measures of appetite, metabolism and endocrine responses were assessed at regular intervals. In addition, eating behavior was quantified by ad libitum assessment under laboratory conditions and in the free-living environment by weighed food record. Acute milk intake stimulated glucagon (P = .027 [16.8 pg·mL; 95% CI: 2.4, 31.3]) and reduced ad libitum energy intake relative to fruit-juice (P = .048 [-651.3 kJ; 95% CI: -1294.1, -8.6]), but was comparable in the free-living environment. Chronic milk intake reduced free-living energy intake at the follow-up visit compared to baseline (P = .013 [-1910.9 kJ; 95% CI: -554.6, -3267.2]), whereas the opposite was apparent for fruit-juice. Relative to baseline, chronic milk intake increased the insulin response to both breakfast (P = .031) and mid-morning milk consumption (P = .050) whilst attenuating blood glucose (P = .025). Together, these findings suggest milk consumption impacts favorably on eating behavior in adolescent males, potentially through integrated endocrine responses.