Pretty good and well-designed! A couple notes:
- There's a bug/exploit once you unlock "Endless Appetite" and it becomes really exploitable after you unlock the "Feeder's Fantasy" Feast. Basically, once you do the first feeding of a date, if you select the priciest/lowest odds option, and then back out of it (selecting "no problem") it changes the likelihood of every option back to start-of-date levels, AND gives you the option of add-ons again, AND gives you the "Maybe she has room for more?" option again, letting you loop this for as long as you have money. You can very quickly pile the gains on and even skip through stages if you're not careful.
- I think you underestimate the mobility and sexual options of people of average height under about 600+ lbs. I think you should also be clear in your description that this game has a heavy focus on health and mobility impacts from extreme weight gain, even around the 350 lb mark. I think it's just a bit too exaggerated compared to reality, especially for the character types who were previously athletic/gym going. It's possible for them to keep some muscle strength going if they are committed.
- To elaborate on the sex, just because someone is fat doesn't mean sex has to be slow and careful. I think you should vary the sex, kissing, and cuddling a bit among the personality types in the future. But don't get me wrong, this game is quite good even as it is.
- A variety of differe types of Feeder's Fantasy feasts for the different locations only makes sense and I'm sure you've already thought about it.
- Sometimes the dialogue during feedings isn't consistent with the stage of weight the character is at. Like for the fitness-obsessed girl to say "I'm gonna have to skip my workout tomorrow" while elsewhere she's described as having trouble moving and breathing.
- I would like if more (or even, any) of the girls embraced the gain kink or revealed that they always wanted it instead of being depressed by it at an extreme size.