Women shouldn’t be afraid to lift heavy weights. Girls are so afraid of “bulking up” that they usually end up lifting five-pound dumbbells all day long and never seeing any progress. If you want that enviable male metabolism, you’ve got to lift weights like a guy. For most women, heavy lifting revs up metabolism and keeps burning calories long after the workout is over -- you won’t get that from cardio alone. The more lean muscle you build, the more calories you’ll burn just sitting still, and you won’t bulk up -- the estrogen in women’s bodies keeps muscles from getting huge and masculine. Added bonus: women who regularly participate in load-bearing exercises have a significantly lower risk of osteoporosis as they age.