Seems like the old "pick something everyone eats and convince them it's the cause of all their troubles" tactic of charlatans.

The science is clear and well proven. No particular food causes weight gain - the number of calories a person ingests as compared to the number of calories they burn does. The reason people always used to say "beer belly" is folks would drink a lot and forget that beer has calories - or not care, and therefore gain weight! Hence the advent of "light" beer, though I do not and have not drunk either kind, so you need not lecture me on the demerits of "lite beer."