When it comes to gaining muscle or losing weight, nothing works better than that glass of milk.

The finding comes from an ongoing study on the impact of drinking milk after heavy weightlifting, by researchers at McMaster University.

As a part of the study, the researchers took three groups of young men 18 to 30 years of age -- 56 in total -- and put them through a rigorous, five-day-per-week weightlifting program over a 12-week period.

After the gruelling workouts, the participants drank either two cups of skim milk, a soy beverage with equivalent amounts of protein and energy, or a carbohydrate beverage with an equivalent amount of energy, which was roughly the same as drinking 600 to 700 millilitres of a typical sports drink.

The researchers found that out of all three, skimmed milk was the one that worked the best, for it helped the exercisers burn more fat.

The group drinking milk lost nearly twice as much fat -- two pounds -- while the carbohydrate beverage group lost one pound of fat. Those drinking soy lost no fat.

At the same time, the gain in muscle was much greater among the milk drinkers than either the soy or carbohydrate beverage study participants, with this group gaining an estimated 40 percent or 2.5 pounds more muscle mass than the soy beverage drinkers, and a 63 percent or 3.3 pounds, more muscle mass than the carbohydrate beverage drinkers.

"The loss of fat mass, while expected, was much larger than we thought it would be. I think the practical implications of these results are obvious: if you want to gain muscle and lose fat as a result of working out, drink milk," said Stuart Phillips, associate professor of kinesiology at McMaster, and lead author of the study.

"I think the evidence is beginning to mount. Milk may be best known for its calcium content in supporting bone health, but our research, and that of others, continually supports milk's ability to aid in muscle growth and also promote body fat loss," said Phillips.

"To my mind -- with milk being a source of nine essential nutrients -- it's a no brainer: milk is the ideal post-workout drink for recreational exercisers and athletes alike," he added.

The study is published in the American Journal of Clinical Nutrition.