A:

While there’s not much research to back that exact claim, your university’s scare tactics to stop binge drinking aren’t totally off base. We posed your question to Matt Barnes, a top researcher on the effects of alcohol on exercise recovery at Massey University in New Zealand, where rugby players have no qualms about boozing in the name of science.

“From what I can see, as long as you follow normal recovery procedures—after training you rehydrate, have a meal rich in carbohydrates and protein—you’re probably fine to drink a reasonable amount of alcohol after that,” Barnes says.

What’s a reasonable amount? That has yet to be determined precisely. Barnes’ research has shown it’s somewhere between one-half to one gram per kilogram of body weight. Below one-half of a gram per kilo, or about 3.5 drinks (with 10 grams of alcohol per drink) for a 154-pound man, Barnes found alcohol did not affect dehydration.

But if you skip the recovery meal, getting your calories from alcohol instead (e.g. a "recovery beer") will hurt your body’s ability to restock glycogen stores. The result: After a muscle-damaging workout like lifting weights or sprinting, your muscles may not function optimally for three to five days.

Drink more than one gram per kilo, or seven drinks for a 154-pound man, and you’re setting yourself up for detrimental side effects that can affect much more than muscle recovery.

“It’ll have a negative effect on testosterone, which is essential in adaptation to exercise,” Barnes says. Cortisol levels will increase while testosterone levels will decrease, potentially leading to shrunken testes, and “beer boobs” in males and affecting the female reproductive system as well.

“When you drink a lot of alcohol, you also switch from burning fat as an energy source to storing fat,” Barnes says. Not great if you’re an athlete concerned with body composition.

THE BOTTOM LINE: If you eat and rehydrate properly after your workout, relaxing with a beer or a glass of wine at the end of the day shouldn’t set you back. But if you’re still partying like a collegiate athlete, tossing back more than 3.5 drinks a night, expect a decrease in performance that can last up to five days.

Want to read more about how alcohol affects performance? Check out Barnes’ studies here.