If she didn't loose the weight and died from heart disease or some other obesity related illness her family would probably sue the doctor for not warning her that obesity kills. Or they could sue McDonalds again.
Yeah - losing weight in the 100's of pounds is unbelievable.
In all seriousness.... the doc's "bedside manner" was probably lacking and it simply made her angry. She's going to have a hard time making the allegations "stick" though.
Not to me, I've done it several times. What's unbelievable, or at least rare, is keeping it off.