Anni:
Speaking from my own experience... Please have a conversation with him about his weight gain before you proceed any further. You don't have to tell him about your kink or that you made him gain on purpose. Just test the waters carefully how he's been feeling about it in general and about his fears and concerns.

I was also responsible for my boyfriend's weight gain back then (it was unconsciously at that time though). He got quite fat and I was very pleased with it but he was so damn miserable. He was suffering and that broke my heart.... Nowadays I would only act on my fantasies if the other person genuinely wants to gain weight. So please, I totally understand your desire but keep in mind that he should have a choice, too. It's his body after all....

BBWKatty wrote
If I typed it all out, it'd be a novel, so I'll summarize. Chubby boy that I turn into a complete pig, and eventually get up to 500+ pounds. I'd force feed him, he'd wear a dog collar, I'd tie him up and stuff him, I'd make him get on all fours and eat from the ground like a pig, and oh yeah, I'd wear a strap on and do him. How's that for kinky?

plenty wrote
Yes, I like a well built guy with broad shoulders and just a slightly fat belly. 6 feet, 200 lbs is very nice. ;-) Even nicer if he starts out slim, and fattens up over the course of the relationship. That is hot!!!