I was about to come on here saying the weight machine was the problem, but after reading through this I'm not so sure: maybe it was digging. But maybe not--I have a male Sim that I dedicated to digging, and he has become really, really fat. I have a female Sim that has also become very fat, and I wanted to change that so I started her working out. She used the weight machine once, and the treadmill 2 times. Then I noticed that she is completely ripped all of a sudden (gigantic muscles), but her hips are still excessively wide. After reading this I remembered that I just had her start to dig for collectibles, but she only dug up a few. The male dug up way more than that and didn't get any muscles out of it. Maybe it is a combination of working out in other ways and also digging (perhaps tied to athletic skill?). Anyway, either way, doing a particular interaction once or even a few times should not cause a woman to look like Arnold Swartzinigger (with big hips). Definiltely, the balance on this needs to be tweaked. It's too hard to lose weight, and too easy to gain muscle.