1. Press F2 to put your hands up.
2. While your hands are up, open the inventory.
3. Right click on the meal or beverage, then eat/drink all.
4. Immediately after that, right click again and "cancel current action".
5. Immediately right click and eat/drink all again.
6. Quickly press the red "x" once to remove the item from your hands.
7. Press ESC, wait until the animation is done, then you can repeat all over again.

After doing all the mentioned steps you will get a message saying that you have consumed something and it will actually hydrate or feed you, but the item used will remain in your inventory, and you can repeat these steps as many times as you want and you will never run out of food. Also, you can do this whether you're on your feet, crouching or proning.

I've heard other players saying that this glitch can be used with any action performed in the inventory (applying a bandage, a saline bag, morphine, etc.) and the item used will remain there, but I don't have confirmation of this.

Please fix this, I think it's not fair. Some friends taught this to me, but I believe that this completely ruins the game.