You talk about attitude, I'm talking about the cellular level, you can beat it permanently. Yes you can choose to be OCD about your weight and diet and live differently from "normal" people ALL the remainder of your life. Yes you can, but do you want to. Being OCD about such things may just kill you from stress.
The point is thin people don't have to fight their biology, they have leeway in life. Once someone has become overweight the leeway is gone.
Becoming overweight IS generally about bad lifestyle. But the reverse, getting back to a lower weight, is NOT. Cellular mechanisms will fight you at every turn.
Do you not understand the cellular mechanism we've been trying to explain to you here? You seem to be living in your own idealised world were the brain is stronger than the biology. I've heard that one before, from faith healers, yeah, just believe a ha ha. You can fight your biology temporarily, you may win some battles, but your brain will not win the war against biology.
So please stop imposing guilt trips on people.