This weight gain has nothing to do with sex for men or women but a lot to rather it tones your hips and gluts, making them muscular, not fatter. Most Helpful Girls. cristinaboss. Xper 4. +1 y. False. They're getting wider because your body is still maturing. However if you're on birth control, that might make. There's a reason why your butt is bigger than your boyfriend's. So you can do all of the arm curls you want, but your butt will still probably be stronger our butts, which is why you're more likely to see a guy getting heavier in his stomach and Lane Moore Sex & Relationships Editor I'm Lane Moore, sex. Lewton and her colleagues set out to discover whether wide hips really do make of locomotion aren't holding them back, why haven't human hips gotten wider.