They'll just keep denying, denying, denying. "Twenty-six-year-olds drop dead from strokes and heart attacks every day!" "There's no way weighing five hundred pounds contributed to her breaking her ankle stepping off a curb!" "Her foot needed to be cut off because of her genetics, not her refusal to stop eating sugary junk after her diabetes diagnosis!"  After all, there will always be new fat randos to tell them what they want to hear. They'll just move on to EvenBiggerFatterScience, who tells them that anyone who's ever lost even a pounds falls into suicidal depression because of it and the only way to be happy and healthy is to be eating 24/7.