As far as I can see, much unwanted weight gain is mandated by hormones. So I told my besty, who is 50, that she might blamelessly allow her waist to thicken, her hair to lose its redness and become grey. It's ok.
I sometimes wonder why so many people have so much trouble with their bodies and diet. It's obviously a really big problem for a lot of people and it very much upsets me, actually, that I have no such problems. I wonder why it's so hard for you. I wonder what it would be like for me if you were my brother or sister, and you had this kind of trouble.
I want to point out that in New Zealand, where I grew up among quite unremarkable children in a small city, only perhaps 1 child in 1000 was obviously obese. We had heard of neither obesity nor anorexia. I'm in my mid 60's.
Nowadays I organise my life for minimal stress and get fresh air and eat fresh food from a tropical market. Maybe that helps