That's not what I want a citation for (but, yes - even that is not a trivial assertion, given that there is a nontrivial part of the population, perhaps even 10% who do not get fat regardless of the amount they eat)
I want a citation that "exercise and diet" are enough to convert a fat person to a thin person. Trivially, that's true - just stop feeding person until they starve and almost die, and then feed a little.
But the non-trivial question is: Given person X who is now fat (possibly a result of binge eating, but possibly a result of disease, some kind of pharmaceutical treatment, etc.) - can exercising and reducing intake alone make them thin, without damaging their psyche, without limiting their intellectual potential and mental well being?
There is NO reason to believe that the answer is a simple "yes". People who claim that the answer is definitely yes should be able to back their claims easily, if this is so trivial.
No, that's totally not what he claims, although that might be what he thinks he argues.
There are enough data points of (thin person, does not exercise or eat properly) and (fat person, exercises and eats "properly") to make that point basically wrong.
Perhaps the problem is with the definition of "properly". But the causation is not total (that is, there are reasons other than food and exercise that cause people to become fat, some known and some unknown), and the population correlation is time reversed to what you would expect (people stop exercising AFTER they gain weight, not BEFORE), to make this not a trivial matter at all.
