Dairy proteins may support muscle protein synthesis and improve satiety in adults. However, there are limited studies using exact measures of body composition, especially in adolescents.Objectives:
This study investigates the effect of milk proteins and water on body composition and leptin in overweight adolescents.Methods:
Subjects (n = 193) aged 12–15 years were randomized to drink 1 L d−1 of skimmed milk, whey, casein (all milk-based drinks 35 g protein L−1) or water for 12 weeks. Twenty participants dropped out. A pre-test control group of 32 adolescents was examined 12 weeks before start of intervention. Outcomes included leptin and dual-energy X-ray absorptiometry scanning. The effects of the milk-based drinks on body composition and leptin were compared with baseline, pre-test control and water.Results:
Lean mass index (LMI) increased compared to baseline (all 95% confidence intervals 0.05–0.50 kg m−2, all P ≤ 0.009) and the pre-test control group (0.044–0.247 kg m−2, P ≤ 0.002) for all four test drinks. Fat mass index (FMI) increased only for milk-based drink groups compared with baseline (0.15–0.67 kg m−2, P < 0.001) and also compared with water (0.029–0.255 kg m−2, P ≤ 0.011). For pre-test control, there was no change in FMI or LMI. Leptin increased in the casein (1.016–3.246 ng mL−1, P < 0.001; 0.952–3.294 ng mL−1, P < 0.001) and whey groups (0.135–2.273 ng mL−1, P = 0.027; 0.069–2.322, P = 0.038) compared with water and pre-test control group, respectively.Conclusions:
Although milk proteins increased LMI in overweight adolescents, there was a concurrent increase in FMI and leptin, whereas water only resulted in increased LMI. Thus, increased water intake may be beneficial for body composition in overweight adolescents.