Giving the player the health 5 effect, then walking into lava or fire, or suffocating in a block causes the player to take damage every tick. A full hunger bar will drain in 10 seconds, but health remains the same. This bug does not occur while poisoned, with an empty hunger bar, or while on fire but not standing in fire; damage immunity is normal in those situations. I had the duration for health 5 set to one minute. Eventually, after the effect runs out, everything returns to normal.