Milk after Exercise Promotes Weight Loss

According to a study, women who drank two large glasses of fat-free milk after lifting weights gained more muscle and lost more fat than women who drank sugar-based energy drinks. Scientists also found they increased their lean body mass and got stronger.

The purpose of the study was to determine whether women consuming fat-free milk versus isoenergetic carbohydrate after resistance exercise would see augmented gains in lean mass and reductions in fat mass similar to what researchers observed in young men.

Young women were randomized to drink either fat-free milk (MILK: n = 10; age (mean ± SD) = 23.2 ± 2.8 yr; BMI = 26.2 ± 4.2 kg·m⁻²) or isoenergetic carbohydrate (CON: n = 10; age = 22.4 ± 2.4 yr; BMI = 25.2 ± 3.8 kg·m⁻²) immediately after and 1 h after exercise (2 × 500 mL). Subjects exercised 5 d·wk⁻¹ for 12 wk. Body composition changes were measured by dual-energy x-ray absorptiometry, and subjects' strength and fasting blood were measured before and after training.

The results showed that, CON gained weight after training (CON: +0.86 ± 0.4 kg, P < 0.05; MILK: +0.50 ± 0.4 kg, P = 0.29). Lean mass increased with training in both groups (P < 0.01), with a greater net gain in MILK versus CON (1.9 ± 0.2 vs 1.1 ± 0.2 kg, respectively, P < 0.01). Fat mass decreased with training in MILK only (−1.6 ± 0.4 kg, P < 0.01; CON: −0.3 ± 0.3 kg, P = 0.41). Isotonic strength increased more in MILK than CON (P < 0.05) for some exercises. Serum 25-hydroxyvitamin D increased in both groups but to a greater extent in MILK than CON (+6.5 ± 1.1 vs +2.8 ± 1.3 nM, respectively, P < 0.05), and parathyroid hormone decreased only in MILK (−1.2 ± 0.2 pM, P < 0.01).

From the results it was concluded that, heavy, whole-body resistance exercise with the consumption of milk versus carbohydrate in the early postexercise period resulted in greater muscle mass accretion, strength gains, fat mass loss, and a possible reduction in bone turnover in women after 12 wk. The results, were similar to those in men, highlighting that milk is an effective drink to support favorable body composition changes in women with resistance training.

The study was conducted by researchers at McMaster University in Canada. A previous study showed men also gained muscle mass and lost more fat by drinking milk after exercising.

The researchers say the combination of calcium, high quality protein, and vitamin D in the milk may be responsible for the changes, but more study is needed.

Medicine & Science in Sport & Exercise, June 2010