I noticed some weird glitches when I decided to gain by myself.
First, with the Reinforced Floor Mattress, you cannot gain past "Blob" when stuck at home (It is also a bit annoying that your food choices are merely "Dizzy's Delivery Service" and "Ordering food", as both of these don't have very fattening options.)
If you decide to replace your Floor Mattress with a Bariatric Care Bed, you will be suddenly teleported to the Resident Chamber. When in the Chamber, looking at yourself and then exiting the self-description will suddenly have you back home or at Gentle Meadows. Eating food will then teleport you back to the Resident Chamber.
Also, when you yourself are on the OnlyFats Top 5 Creators leaderboard, it only shows you if you click on "Full Rankings". I am not sure if this only happens if you gain yourself, or if this is an issue with the other girls that you pimp.
Lastly, this isn't a glitch, but the inability to change fat faces, player weight gain, health issues, etc... during the game is a bit annoying. If this cannot realistically become a feature, then just consider this a minor nitpick.