You know little about the human physique. Athletic girls with ''slim hips'' didn't burn too much fat, women have relatively little fat on their hips unless they're overweight. Women who do sports build a strong and thick core thus somewhat eliminating the hourglass body shape, a common ''problem''. Hip width don't change neither does shoulder width, its bones sticking out of your body. Also happens with men, its the main difference between body builders and strong men. The latter have much wider cores because they pack more muscle (obliques). Bodybuilders even do a special exercise to ''pull in'' their obliques and abs to get a slimmer waist - they do vacuums every single day.
Anyway.