I have only tested this in 1.11.2 as of now. In singleplayer, in said version, if you attempt to eat or drink anything, the eating/drinking animation on the item stops at the normal point (32 ticks). However, the food/potion effect/whatever the item does on use does not get applied. You must hold the right mouse button down for approximately 32 more ticks past the end of the animation, during which time you will still hear the sound effects (and see the particles flying in the case of food), and at the end of this period you will then receive the effect of the item and, in survival mode, the item will finally be used.

This does not seem to happen in multiplayer, which is somewhat confusing to me. I would like to point out that this bug really does effect all food/drink items, too, as I discovered it while working on drinks in my mod KalStuff. I thought it was a problem with my code at first, until I noticed that it applied to Vanilla as well. So I have tested it with and without any mods whatsoever; same result every time except for in multiplayer.

I'm not a pro at reporting bugs, so please let me know if I can improve anything or need to provide more information on this.

UPDATE: I have now decided that it does not take twice as long, as I had mentioned. It just takes at least twice as long, sometimes longer.

UPDATE 2: I realized that I should mention the problem is not with my computer hardware/lag. If I host the server myself on the same computer, the bug does not happen. As I said, it only occurs in singleplayer.

UPDATE 3: The issue seems to be resolved in 1.12.2.