Hunger

Hunger is a removed feature from the game. If your hunger got too low, you would lose health.

Eating
Your hunger bar (on the top of the screen) would slowly deplete over time. Eating any food item in the game will restore it. If you do not eat for a long time and your hunger bar gets low, you will be reminded to eat via a notification. Continuing not to eat would result in you losing health.

Trivia
If your health/hunger bars were completely full, the bars would disappear but the icon would not.

Hunger was removed in a 2020 update, thus making all food items useless.