Take the Plunge

Running stark naked into the ocean in winter might seem loopy. But a new Scandinavian study (where else?) found that young men who spent at least two years swimming twice a week in cold water, then recovering in saunas, burned more calories via brown fat (type that keeps you warm), which promotes weight loss. In the wild, swim naked: Clothes cling to skin, making water feel even colder. If you’re prone to “icecream headaches,” use earplugs to keep water from entering your ear canal. And skip the shot of whiskey. Booze lowers your body temp.