There are countless reasons why you shouldn't party like a frat boy. Overdoing it on alcohol has many negative health impacts, and your bones aren't spared the damage. "Drinking in excess impairs normal function of the liver, where vitamin D from food, supplements, and the sun is converted into a form your body can use," Recker says. So if the liver's not working right, you won't get enough vitamin D. Experts also think alcohol messes with the hormones that help the body absorb calcium, leaving you void of another key bone builder. But this doesn't mean you should cut out cocktails completely. Studies show that moderate drinkers have better bone density than nondrinkers, and having one to two adult beverages a day may actually promote bone remodeling. Just keep it in check.