Weight issues with my daughter

My daughter is 15 5 foot 0 with a bing. She had a doctor's appointment recently and I know it made her feel horrible about herself. She is considered morbidly obese. She's almost 500 pounds and it's getting to the point she can barely walk. Her doctor told me if we don't change her life style she's gonna have diabetes before she's 18. But I've tried to stop her bing eating. Her self esteem is so low and I'm not sure what to do anymore.