Sucking fat from your hips, abdomen, and thighs and injecting it into your boobs or butt is called fat transfer or fat grafting. It involves removing fat from one part of the body via gentle liposuction and then injecting it elsewhere. It works well all over the body, but is most commonly used on the face to enhance cheeks, fill hollow lower eyelids, and build up areas that have lost volume due to aging.