You must not train or eat like me then. I'd bet you never took it as far as you could natural with diet, intensity, and consistency. If you at 8x a day all good food for months straight, zero deviations, then I would agree you could not gain weight naturally.
I have a very big frame at5,11 6ft i am an endomorph mesomorph i have hit 280 natural gaining from weight training by lifting heavier than normal than at 225 and consuming 30% more calories of that 55 pounds i gain 1lb of fat for each lb of muscle trained, and i look like a fridge.I have found the best waist to lean ratio for me is 32 inches at 225 lean.That why i dabble in steroids 270 lean as i am at 225.
I cannot change my metabolism the first Four years natural i tried to gain lean mass from Hydroxycut to every natural fat burner i trained up to twice a day ate clean religously tried everything to Hit training thats why i succumbed to roids seeing bodybuilders juiced with crappy routines lazy work ethics getting huge.
Trust me getting clean from rec drugs i busted my ass off for the first 4 years of training natural and i hit my bodyfat level at 8%.Not big noting myself but there are not many naturals at that size i am lean.End of story.
PS i have not trained in 4and half months due to an altercation at the gym and currently 290 with a big waist i do not really care as my state of the art home gym will be built in 3 months this is the first time i have not trained consistently for 10 years.