There is a golden rule of attractiveness for the waistline compared to the buttocks, and that is the rule of the 0.7 ratio. If the narrowest measurement around the waist is divided by the widest measurement of the hips, the ideal number you can come up with is 0.7. Everything above that means there is a bit of hip excess, and everything below that value means the waistline is not as slim as it should be or the hips are too thin.

The Brazilian Butt Lift is a surgery that addressed just this situation.  Liposuction is used to improve the waistline, while the same fat is used to improve the shape of the hips.