But you are still assuming that the metabolism is effectively qualitatively identical. I.e, that the only thing changing is the quantity of calories burned rather than how the excess calories are used. Part of what makes this research fascinating is that it raises doubt about that, which isn't really surprising given what we know about Cytochrome P450 variance and pharmaceutical metabolism. Some people, for example, do not find vicodin effective because the pro-drug is metabolized much slower than the active metabolites....