Minecraft wiki entry for Healing, associated text: If the player's hunger bar is completely filled and they have left over saturation, this saturation gets drained, healing at a rate of 2 every second. Just as with the hunger-based regeneration, every 1 regenerated deducts 1.5 saturation. With the maximum amount of 20 saturation, the player can rapidly regenerate up to 13 × 6.5.