Hunger works with 3 different statistics:
- Exhaustion (an invisible value that explains how the player becomes hungry)
- Saturation (an invisible, second hunger bar)
- Hunger (the hunger bar)
(1) Exhaustion is quite easy. It is a value that starts at 0 at resets at 4. Every action in the game like sprinting, swimming, jumping adds to exhaustion (for example if you jump 80 times, exhaustion goes from 0 to 4) every time it hits 4 you will lose one hunger point and the value changes back to 0.
This hunger point gets removed from 1. the saturation and if now saturation is left from 2. your hunger bar.
(2) Saturation is, while simplifying a bit, a second invisible hunger bar. All food you eat gives both saturation and hunger.
(3) hunger is simply the bar you can actually see and works the same as saturation.
So now, how does 1.9 differ from 1.8?
in 1.9 when the player has ANY saturation left, his hunger is full and his health isn't the left over saturation turns into health. This happens until the player is full health, or no saturation is left. 1.8 doesn't have this feature.
Sources:
Difficulty is an option in Minecraft that has a direct impact on the ease of gameplay, allowing the game's challenges to be tailored to the player's skill level. There are four difficulty levels in the game: Peaceful, Easy, Normal and Hard. These can be changed when creating a world, in the...
minecraft.gamepedia.com
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