Yup, it won't do her any good unless she makes changes. And I'm sorry, but all that weight didn't get there from pregnancies alone. You have to want to make a change, she's just looking for an easy way out. Eating healthy and working out take discipline - it's not easy.
My aunt had gastric bypass when I was young, about 25 years ago. She refused to do as the Doctor advised and would eat until she threw up, then eat some more. She's lucky she didn't die. She's still as heavy as she was then.
I agree - she has to make changes. People like this do have an eating disorder, though - so they really need counseling and medical help to overcome thier food addictions and emotional/psychological issues. This is not just a will power issue, it goes a lot deeper than that - you have a combination of emotional, psychological and the physical. The truth is, at her size, she probably does need a medical intervention, but it should come with counseling and nutritional support.