"That more people are entering than leaving doesn’t. It’s what logicians call “vacuously” true. It’s true, but meaningless. It tells us nothing. And the same is true of overeating as an explanation for why we get fat. If we got fat, we had to overeat. That’s always true; it’s obvious, and it tells us nothing about why we got fat, or why one person got fat and another didn’t."

I was following along with the analogy, but this really bothered me. "If I am fat, then I ate more calories than I burned" isn't vacuously true (because there are people who are fat), it's a tautology.

I don't know anything about nutrition, but seeing an error in the small part of the article I do know something about makes me more skeptical as to it's premise.

EDIT: After a few more minutes thought, I have to mention that since we've all eaten more calories than we've burned (or else we'd be massless), the statement is true for everyone, not just obese people. But that's just me being needlessly pedantic.