I extracted the game files (version 0.1.00, which was up-to-date when you wrote the comment but no longer is) and it seems you are right. I don't fully understand all of it yet but I think
- There is an oversight that you can survive without drinking, probably will be fixed
- There are six transformation paths:
- "anorexia" (starving): 3 levels then death
- "unhealthy" (sweet, fatty or rotten food, some is also anomalous such as choco shapes or donuts): 5 levels
- "perfect" (healthy food): 5 levels ranging from beautiful to muscular to space being; contrary to popular belief all healthy food counts but apple seeds are easiest. I think only number of items counts, so 10 apple seeds are as good as 50
- "parasite" (worms and bugs including giant alien ones, bees, maggots, earthworms, wasps, crickets, scorpions, but not fried roaches, tadpole soup, snail skewers, milk spiders, rat on stick or dog feet): 3 levels, ranging from maggot-infested to insect queen
- "anomaly" (SCP food: human body parts, spiced candy, leeches, bag of colorful apples, lemon clams, fluffy alien box, pyramids, choco dildo/floppy/chess/robot/bullets, Ponari Sweat, swimmer bottle, Xocolatl, can with alien language): 3 levels
- "liquid" (drinks): makes your belly and head very round and full of ulcers, idk if it even works: 3 levels
- Starving or eating/drinking non-category-specific food will decrease level in category
- Idk if you need to return to normal to change categories
Costs:
- ¥1-¥10, ¥50 only gives corresponding amount of seeds
- ¥150 only gives unhealthy liquids
- nothing costs over ¥1000
- no parasites above ¥300
- seeds are best satiation for your buck:
- theoretically best is 1 seed = ¥1 = 1 satiation point (but you'll spend too much dispensing them they're not worth it)
- likely best is 10 seeds = ¥10 = 5 satiation points
- also good is 50 seeds = ¥50 = 10 satiation points
- best parasite chance: ¥100 (26 %), same as ¥300 but that's not worth it
- best anomaly chance: ¥500 (59 %), or ¥100 (22 %) for best value
- best healthy liquid chance: ¥100 (11 %) (needed for "liquid" route, presumably)
I'm guessing that your best chance at surviving, making money and staying normal is by eating 10-packs of apple seeds and occasionally ¥150 junk drinks to reduce healthiness and thirst (if a thirst consequences get patched in a future version). You'll save up to fill the inventory with various things. Eat a selected category at once to transform as you wish. Only eat on the street to waste less time not begging, although looking into your inventory next to the vending machine is the only place to see the front standing sprite.
In the game files, you'll also see unused sprite versions with an open mouth (perhaps for eating animation that didn't really work, may be fixed later), traces of a "mother" mechanic and the script for a little VN I don't think was released.