The size of human ilium is controlled by genes. In adolescence, calcium intake will affect development, but it will not be targeted. It's for the whole body ilium. If you want to change its normal development simply for the sake of beauty, it is really not worth the candle. If your desire is too strong, you can have plastic surgery and osteotomy as an adult. Wear low-slung trousers with a nice belt, because the hip bone is very big. If you buy pants or skirts, you must have a waistline that fits your hip. If the hip bone fits properly, the waist will be loose. My friend is dressed like this now. Everyone says it looks good, saying that her waist is very thin, and some people say that the belt looks good. There won't be such troubles again! I also hope you can make new changes!