Yeah, this is my belief, but I didn't want to come off as an asshole. I'm naturally big. Gaining weight was never an issue for me, so I try to be more forgiving when other guys say they can't. But that's not my inclination.
You see, I can't tell you how many small guys (like back in high school, playing football) said, "I wish I was your size, I can't gain weight."
I would always reply, "Well, you're not eating enough."
Of course they always say, "Yes I do. I eat six meals a day. I take weight gainer four times a day."
I say, "Well, okay, that doesn't change my advice, you're still not eating enough."
Then they get smart, they say, "I've tried that. You're not listening. Shut up. You don't know my diet. You don't know how much I eat. I eat like a horse."
So I say, "Okay. You need to eat like two horses."
I don't want to be a jerk, because, like I said, I was never small, but at the same time, I want to say, "What do you want me to do, stroke your vagina for you? That's not gonna help you gain any weight either."