What the last decade or so of obesity science has shown us, is that this is far more complex and involved than we were taught or ever thought possible.
e.g. the experiment in which the gut biome of two adult humans was extracted. They were identical twins with the exception that one was obese and one was a healthy weight. That biome was given to two mice who were then fed exactly the same food as each other. The mouse that had the 'fat twin; biome got fat. The other mouse did not. One mouse did not have mroe willpower than the other.
e.g. the understanding now of the variation in leptin and ghrelin responses across individuals and how those differences allign with weight.
e.g. the biological warfare that is ultra processed foods, with millions of dollars going into researching how to tweak these 'foods' to make your body demand more and more of them.
e.g. the WLD that are rebalancing hormones, and in doing so suddenly these 'lazy, greedy' people are making far different food choices. Not just the amount of food, but the types of food is being changed. And they are active more often even before the weight comes off, as inflamation is reduced and leaves them without everyday pain etc.
Many obese people have shown they have the willpower to lose several stones in thier lives. But there has to be a reason that these disciplined people 'suddenly' find they cannot maintain that loss. Less than 5% of people who lose significant weight keep it off for more than a year. When you see what weight loss does to leptin levels (10% of body weight loss, more than halves the leptin your body produces) and ghrelin (10% weight lost more than doubles ghrelin levels) you realise that significant weight loss triggers mechanisms in your body that significantly decrease who full/satiated you feel after food and significantly increase hunger levels. And that goes on for months, years after weight loss - even if you put the weight back on.
This stuff is multifactoral and is not about self-control anywhere near as much as was commonly thought 10-20 years ago. It bigger and more complicated than that.