I think it's more about what your exposed to. People at young age are especially impressionable.

Its logical to assume their is some people have experienced something with those close to them that benign or traumatic led them to this fetish. Its also logical to assume that through purely random or coincidental exposure one could grow a fascination.

I think for a majority of people while one might identify the former or the later as their point of origin. In experience though its likely a combination of the two that brings someone to identify with the fetish. Although im sure there are exceptions.

I don't know. To be honest not looking to gain.

But anything over your Basal metabolic rate will lead to weight gain. There is calculators online to get a rough approximate.

Rule of thumb apparently is 3500 cal over bmr is 1lb gained. Do with that what you will.

Not a doctor might be worth doing your own research. Try to stay heathy-ish

Yep that is unhealthy obsession. Geez.