Experts say guzzling a post-workout protein shake can help muscle recovery and growth, but what type of protein is better, whey or casein? A Canadian study revealed last week that whey protein may be your best bet. “A whey protein shake would probably be better than a casein protein shake,” says researcher Daniel WD West of McMaster University in Ontario. The rationale? While both proteins are found in milk, casein is digested slower than whey, and after a workout, the body responds best to a fast-acting protein.

Another new study from the US Army Research Institute of Environmental Medicine that was also announced last week reveals that protein supplements that include higher concentrations of the amino acid leucine work better than those with lower concentrations. In the study, active-duty military personnel drank a high-protein beverage that contained either 1.87 gm of leucine or 3.5 gm of leucine while riding a stationary bicycle. “It appears more leucine is beneficial in muscle recovery,” says researcher Stefan M Pasiakos, PhD, a research physiologist involved in the study. Both studies are published in the American Journal of Clinical Nutrition.

How much protein should you drink? Experts recommend not overdoing it and sticking to around 20 grams  after your workout. “Some protein for repair is good but not an excess,” advises Felicia Stoler, a nutritionist and exercise physiologist.