General

Strength athletes are often fat and building muscle involves bulking. I wonder how much these world's overlap.

In what sense? You think some members of these sports have a weight gain fetish or do you mean something else entirely?

I mean, I have known people who wanted to be 'strong fat'

On top of this, a lot of the weight gain advice you see in feedist spaces also exists in bodybuilder spaces, minus the exercise intensity. It's funny how much overlap there is.

I mean, "Bulking" is the muscle gaining phase at which you're meant to consume more calories than you need to promote growth. Those who prolong the bulk will pack on fat as well, it's inevitable.