alt Hacker NewsIt is not just issue of raw calories but how much body can absorb. Fruitarians for example tend to be corpse-skinny despite fruit being full of sugar, because most of that sugar simply passes through. So effective calories are less than what sugar content would indicate.
But grains and seeds do seem to be quite obesogenic, yes.
I add the word "obesogenic" to my toolbox, love how it sounds!
I don't know Fruitarians but what you describe makes sense. However the vegans I know aren't "Hungry all the time". Some are skinny and some fatty but I wouldn't say the average are skinny, you wouldn't stare at their size if you don't know their diet. Might be a personal bias though, I don't know studies about vegans hungriness or BMI.