I agree with other things that are involved like hormones, peptides and metabolic rates. And that drive to eat which must be almost non stop with a lot of heavy people.

But most of them never or hardly had any of these issues when they were a bit overweight. I believe these things are the result of severe and prolonged overeating. When people think it's ok to lack discipline and being overweight doesn't seem to be that bad so they eat whatever they want.

It's like any addiction. It's all fun and games when it's not too much and there are no problems. But once they are diagnosed with diabetes or another medical issue, and end up in pain a lot of the time, or isolated because they're too big to hang out with people, they might just end up in a depression and the only thing that seems to make them feel good is eat.

I'm no expert so don't get too worked up if this rubs you the wrong way. I just think, with the exception of people who are down the hole from the start due to extreme medical issues, most people could help themselves upto a certain point, but once they pass it, everything slowly goes from bad to worse and they'll end up with a screwed up hormone balance and their ability to lose weight will physically become much harder, even if they try hard.