This is impressive but the pacing is really off, presumably because gain isn't scaled well. There should be an exponent on gain as well as the player's size, so larger objects count for more.
E.g. you actually track the player's volume, and add objsize^3 volume whenever you eat something. (Probably with an added multiplier to keep things working.
Also going from city->island is a weird spot currently since there aren't many things you can eat. There should be edible things on some of the nearby islands.