About Leveling Up, by Only Eating! Manga:
The main character is stricken by a rare condition that affects only two people in the entire world, bulimic deficiency.
He organizes his daily meals to survive, but his hope of survival grows dimmer as the days go by.
He consults a doctor, who suggests playing the Alternate Reality Game ‘Athens’, where he can eat as must as he wants without gaining any weight.
He plays the game to save his life and grow in strength by doing nothing but eating!
A Gourmet Fantasy Life!