I don't think you'll find as many people yelling at you about fat sympathy as you expect. This is the off-topic thread after all. Most of my FPH vitriol has been fueled by my general hatred for laziness & mediocrity and my difficulty in finding love when statistically, most of the population physically around me repulses me. But that's the thing, I can simply choose not to associate with these people in my personal life, as numerous as they may be. You don't have that choice because that's your man's daughter and she will always be a part of his life and by extension, yours. I'm not a parent but I understand this.  Someone posted a while back that yelling at someone until they have a normal BMI is generally not the best solution to the obesity epidemic. Aside from very impressionable males (e.g. 18 year olds in boot camp), I agree. People tend to double down on their bad behavior when called out on it, and this is likely to happen if you sit her down for a "let's talk about your weight" conversation especially when her only closer female parent figure is basically telling her to do whatever the hell she wants because letting your daughter make the same bad decisions you did validates your own bad decisions. The only advice I have to offer is completely vague and probably useless but I wanted to type it up because you deserve it. I don't really try to help fattys anymore because so few of them stick with advice or are willing to put in any work but in the past the best luck I've had was to find something they're passionate about that's NOT food and want to do and point out how inconsistent that is with being fat. The closest thing CD has to a happy-ending fat-to-fit transformation story is I got one of my 65 year old, overweight but not obese, former coworkers to go on 5AM morning walks with me for almost 3 weeks in a row by explaining that walking at a fast pace for 20 minutes every day would mean he doesn't have to be out of breath and in pain when he's going down the trail to his favorite fishing spot. It didn't last because muhh pain, etc but it's the most success I've had (I just didnt really have the lack of heart to pull the "CowboyDancer is in pain every day from sports injuries and still somehow struggles out of bed" on a 65 year old dude). Your SD sounds like an adult age child and that's the mentality that allows someone to become 400 lbs so you've got a hard road ahead but there's gotta be something she wants that doesn't line up with being a fatfuck (Chris Pratton? Ryan Gosling? LOL). FWIW you sound like a wonderful mom and I'm very glad that there's people like you out there.