Figure out a compelling answer for what that explanatory factor is, and you'll be a billionaire.
Chalking it all up to willpower is, however, unconvincing. When I managed to get down to ~22 BMI awhile back using the willpower approach, I spent literally every moment distracted and obsessing over the food I couldn't have, for months on end. That's not something that most people at 22 BMI do (unless you think that they also use their willpower to quash the constant intrusive thoughts). It's not a huge leap that others who struggle with getting to a healthy body weight experience something similar, especially because it's what they report happening. I wouldn't be surprised if the people who fail outright have even stronger cravings than I did.
What about 90% willpower? 80/20? I'm willing to go below 100% on ascribing this to willpower, but probably no lower than 70%, just based on the outcomes for folks who have willpower and for folks who don't.
There's just too much evidence supporting the idea that actively eating less and continuing to do so is a successful strategy for losing weight, combined with the obvious fact of simple human biology that eating involves consciously taking food and putting it into your mouth (sleep-eating notwithstanding).
I hesitate to speculate; for any individual, it could be a different mix.
It would be an interesting test to correlate obesity with other non-food related willpower tasks. If the correlation was high, on a population level I'd lean more toward willpower being the dominating factor; if the correlation was low, more toward the catchall non-willpower factor.
But you already speculated by claiming it's not 100%. So either you have another number in mind or are just being contrarian...
Further, your experimentation has a flaw; no two things carry identical risk factors and "willpower" factors. Food, as anything, is unique, so the idea of comparing it to other willpower exertions isn't relevant.
> Food, as anything, is unique, so the idea of comparing it to other willpower exertions isn't relevant.
So, you're backing away from the idea that people who struggle with weight lack willpower and are shifting to the stance that they lack some hunger-specific willpower that's unrelated to anything else meaningful?
That's completely indistinguishable from the idea that some people feel hunger more than others.
Nope, I’m reasserting that applying willpower to food consumption is completely possible, and to claim that willpower isn’t a skill is to deny decades of research that shows over and over again that it is.
Chalking it all up to willpower is, however, unconvincing. When I managed to get down to ~22 BMI awhile back using the willpower approach, I spent literally every moment distracted and obsessing over the food I couldn't have, for months on end. That's not something that most people at 22 BMI do (unless you think that they also use their willpower to quash the constant intrusive thoughts). It's not a huge leap that others who struggle with getting to a healthy body weight experience something similar, especially because it's what they report happening. I wouldn't be surprised if the people who fail outright have even stronger cravings than I did.