Think of it like an average person turning bodybuilder. The average person needs 2,000 calories a day to sustain themselves. If that person starts working out intensively to become a bodybuilder, and puts on 40 lbs of muscle, the same 2,000 calorie diet doesn’t work. They’ll be hungry and fatigued because they don’t have enough calories to sustain their mass.
As you progress in this game, you’re also building up strength to live, which shows in your health and stamina bar increases. The amount of food you demand will naturally increase as your body adapts to the needs of survival. It doesn’t show up in a metabolism that demands more food per hour/day, but it does show up in the amount of food and water you must maintain to operate at full levels.