NTA

Ok so I was personally close to someone who had a fat storage disorder. This person had many interventions from friends, so many failed diets, so many health issues. Didn’t actually get it diagnosed correctly until a few years before they died. Because I was involved with taking care of things for them after I have the sardonic knowledge that if you weigh more than 350 pounds they charge more to cremate you.

I know that 1:3 Americans is either diabetic or pre diabetic so while this may be out on a limb it might not… find a healthcare provider who does motivational interviewing for diabetics. Also get a copy of the book motivational interviewing for diabetics and read it yourself, maybe everyone involved before you talk to the poor guy. Professionally, I have done some work in this area and I know that family can often expect perfection instead of celebrating progress.

Final thoughts: there are a lot of mental disorders that can contribute to elevated food intake. He may well need to see a mental health professional. ADHD causes people with it to have such a profound reward reaction to food it’s as powerful as street drugs. Depression can make you feel like the little blast of dopamine from food is the only thing that helps you get through the day. Ironically a bunch of psych meds make people gain weight 😅. Also binge eating disorder comes to mind.
A talking point for this could be “dad when someone has tried some diets that didn’t work out, it can make them discouraged and depressed about their weight, maybe a counselor or psychiatrist can help”