I'm being pretty overt that when people make that claim they are often being dishonest. They know they are eating too much. There are psychological issues underlying this, but if someone tells you how little they eat yet they're gaining weight, they're likely lying.
> And, despite your claim, there are also demonstrable differences in the base metabolic rate between people.
Nowhere did I contest this. Men have more muscle mass than women and are generally larger. But between people otherwise equal, claims about varying metabolisms are largely bullshit. It is magnitudes less of an influence than it is held as.
I've been cited as a "fast metabolism" examples many times in my life. I skip meals constantly, can manage to go through a movie without eating a bucket of butter-soaked popcorn and a jug of coke, etc. I eschew all of those things. Then there's a bbq and I eat two burgers and the upper BMI people all gather around to tell the tale about how easy it is for me, what with my "fast metabolism". It's horseshit. It's destructive, self-enabling nonsense.
Another guy mentioned that when his belt size starts getting tight he knows it's time to cut back. Precisely my tactic. There have been a few times where suddenly slacks are a little tight and it isn't a signal that I need to buy new clothes or go to the next rung, but instead means it's time that I skip the occasional snack.
The fact that they are overeating doesn't mean that they aren't also feeling very hungry, truthfully. And again, neither you nor I know if it's a psychological issue or metabolic or endocrine or anything else (or a combination).
These are the two key facts that the article is discussing and you are completely ignoring in favor of feeling superior about your self control ("I can go through a movie without eating a bucket of butter-filled popcorn").
I take great issue with you saying 'they claim to starve themselves'. The entire point is that people who are obese can feel that they are starving while eating twice the calories that they should. Some other people feel full after eating half the calories that they should. This is the almost the entire problem, the unexplained difference.
And, despite your claim, there are also demonstrable differences in the base metabolic rate between people. One of the most basic is the difference between men and women, which is usually estimated to be about 25% — men are generally accepted to have to eat about 2500 Cal per day to keep their weight, while women should only eat about 2000 Cal (for example, by the NHS [0]). There is no reason to think that, if there can be a 25% difference in the BMR between men and women, there can't be similar differences between individuals as well. Of course, you won't find anyone who eats 10k Cal and is not gaining weight (outside professional athletes, perhaps), or anyone who is eating 100 Cal and not losing weight. But it's quite plausible for someone to eat two extra pizza slices and still lose weight compared to someone else.
[0] https://www.nhs.uk/common-health-questions/food-and-diet/wha...