Minecraft wiki entry for Quick_ways_to_get_food, associated text: Rotten flesh is one of the most common and least-valued items in the game. Most often found after killing zombies and their various relatives (or waiting for them to burn in the morning), it can also show up chest loot. It is a bottom-tier food, which furthermore has an 80% chance to inflict "food poisoning" -- 30 seconds of the Hunger effect. However, that duration doesn't accumulate, and it doesn't cost all that much hunger. So, if you eat several pieces at once, you can fill up your hunger gauge, perhaps heal a bit, and only lose a little saturation "off the top". Drinking milk right after eating rotten flesh will also cancel the effect.