” if achieving health is only a matter of raising the metabolism, and raising the metabolism (besides obvious lifestyle factors) is as easy as just eating a bunch of food without restriction, how do you explain people like me for whom this approach plainly fails?”
I would agree with you on this. Obviously, some people have other factors going on, like genetic factors or past traumas and emotional problems, or major imbalances. Eating a lot to try to raise your metabolism won’t fix that stuff, and can probably cause worse problems.