I swear every now and then a post asking for game recommendations will pop up and I will keep suggesting the same one’s lmao
Play The Lipomancer’s Ruin by Somchu. The game is mostly a RPG but your interactions in the town involving NPCs note on the players weight.
Alternatively, Abducted Plus+ which was also, originally made by Somchu and later picked up and continued by ToshDragon is very much about “studying” the player’s weight gain after being abducted by aliens.
Im sure there is more but none as memorable (for me) as these two I just mentioned