Also, it's not about losing weight, it's about staying at that level long term.
Assume for a second some people are predisposed genetically to end up at a much higher weight than others. These 'fatties' might force themselfs through immense effort to resists their bodies innate tendencies and lose some pounds. But for the rest of their life, staying at that level will be a constant fight against their nature for them.
While people like me never gave one shit about our body weight and just stayed at our level anyhow. When I eat 2 whole packs of sweets one night, I feel no desire to eat the next morning. My body inherently keeps me around the level I'm at now without much effort. After I gained a lot of weight while trying out some medication it took me a bit, but without really trying that hard I got back to my original weight while kind of just forgetting about the whole thing. I didn't earn these traits and I shouldn't assume the same things would work for everyone else.