Bulimia and drugs from the looks of it. The bloating you get from bulimia and the on again off again weight gain/loss would explain the saggy butt and also why her stomach looks abnormally tight. She probably got a tummy tuck for any loose skin in that area.
Oh gee, how did I know the title was sarcasm right away? I do miss the Tara Reid from 200...2? Damn it's been a while.