The theory calories-in-calories-out doesn't explain why animals fed controlled diets over time could exhibit a change in weight, pretty much by definition. So i

The theory calories-in-calories-out doesn't explain why animals fed controlled diets over time could exhibit a change in weight, pretty much by definition. So instead of trying to extend that paradigm in some way that would explain it -- or even to acknowledge that there could be some auxiliary cause for this phenomenon while saying it's irrelevant to the trends in human obesity, which I think would be a fair argument -- you're saying 1) they aren't actually being fed the same thing, 2) they aren't actually being fed the same thing, 3) they aren't actually being fed the same thing or they aren't actually gaining weight. This is only "most likely" if you begin by assuming the truth of what's to be proved, i.e., begging the question.