That's 139 grams for a 180-pound man. Men who work out 5 or more days a week for an hour or longer need 0.55 gram per pound. And men who work out 3 to 5 days a week for 45 minutes to an hour need 0.45 gram per pound. So a 180-pound guy who works out regularly needs about 80 grams of protein a day. Now, if you're trying to lose weight, protein is still crucial.