Consumed food will first fill a stomach bar that will over time be digested to fill your normal food bar. This means eating food does not refill your food bar immediately, and food effects like golden apples will only apply after the food has been fully digested. At the same time the 20 units of stomach bar means you can go longer between eating.

Having more than 20 units of food in the stomach bar gives a Overstuffed debuff while a Strong Stomach potion can remedy that ailment.

Digestion Mechanism:

All food in the stomach is digested at once with a bias for digesting food eaten earlier. Different foods digest at different rates, food with higher saturation values takes longer to digest.

Eating too many food items at once can slow rate of digestion, because food digestion is constant but spread across a large quantity of food items.

Potion Effects:

Overstuffed: Every second there is a chance you get a Vomiting effect of equal level, probability increases with effect level

Vomiting: Slowed and lose all food units above a certain minimum, minimum starts at 10 and decreases with effect level

Strong Stomach: Protects against getting Overstuffed effect, every level protects for the next 8 food units