Cool game concept. I like what you're doing, and I love Velvet. I'm not a chubby chaser, but I'd chase her, lol. If you're open to suggestions though I think you're thinking too small with the fitness system for the heavier girls. I honestly think you should apply the system to all of the girls, Since you're players preferences and going to swing both ways for weight, you'd probably get more interest if you had an option for the fit girls to gain weight. You're already incorporating the mechanic, so why only use it on some characters. Having the MC be able to encourage the fit girls to let go and relax, you open the door to a wider audience. Basically I think going the extra mile and incorporate gain weight, staying as is, or getting fit for all the characters would help get the game out a more niche audience.
Anyway, keep up the good work. I'll keep an eye on the game. And don't let the AI hate get to you. It can be brutal from what I've seen. Distain for the misuse of the AI companies doesn't justify shitting on a real people's hard work and effort. Best of luck bud!