Here’s some early game pointers if someone wants to gain quickly:
Slow progression seems to be a common problem for people starting out - do not just sit in your room and stuff yourself at the fridge, and do not just eat until you’re full then go to bed. Your capacity will not increase meaningfully, your character will just eat until they’re full and then fall asleep. It’s stunting your progress. Until you have the stomach capacity to actually empty the fridge and still be active for the day, filling up first thing is kind of a trap. You only want to get full outside your room so your day doesn’t immediately end.
You are expected to do some random wandering. If you want to speed up your gain and increase your character’s stomach capacity to help that growth accelerate, pay attention to how and where you eat. If you stuff yourself in your room, it immediately sends you to bed or prevents you from leaving, which means you can’t overstuff yourself past your limits.
Note in the self-examination descriptions how full you are, and try to only trigger additional “forced stuffing” events when you are already nearly full or totally full from regular eating. You will know these events as you encounter them, because they usually catapult you into “food coma” fullness no matter what level of fullness you start at.
I usually eat a decent amount in the morning (I make sure my character has breakfast, which can gradually get larger as they do), then using that energy to go for a walk/exercise. Exercising regularly at an early stage is actually really helpful because it has a chance to increase your stamina, which you’ll need later to get more actions once you’re fat.
Fill up by accepting snacks and eating through other random events throughout the day. The cafeteria is great early on if you wanna get at or near “food coma” status quickly without immediately having to fall asleep in your room. Just hang out with the engineers multiple times.
You should save your daily doctor’s appointment for the very last part of the day. There is a possible event where the doctor will stuff you full of food, and even if you are already totally stuffed, you will be fed the same amount of food, well beyond your current max capacity. This is going to really help stretch your stomach. Then you can go to your room to end the day.
As you get a little bigger, the couch is a great place to sleep for the night. There’s a chance that watching TV will trigger a snacking event with a servant robot or the doctor showing up. The food from this event will ALSO overstuff you, since you’ll eat it no matter how full you already are.
You could, if you’re really lucky, get stuffed while already full at your doctor’s appointment, and THEN get stuffed AGAIN while watching TV. You’ll then pass out watching TV, and will have maximized your stuffing potential for the day. Behavior like this will pretty quickly increase your stomach capacity and speed up your gains.
Once you hit 750 the game progresses to chapter 2 and a bunch of new random events and places to explore open up.