When holding right click when your hunger bar is full your hand will bob up and down uncontrollably. This works when food is in either the main hand or off hand. This also applies to other items such as splash potions.
Linked issues
is duplicated by 5
MC-82947
Attempting to eat food when not hungry causes item in hand to go down and up
Resolved
MC-83102
Trying to eat food when your hunger bar is full makes the food move up and down as if you were trying to place it.
Resolved
MC-84408
Using both hands potion throwing
Resolved
MC-86397
Spazmatic shield movement whilst eating food
Resolved
MC-87478
Food (interact) Bug
Resolved
I can reproduce this.