Summary:
When you're at a low hunger level (3 bars or less) and enter Spectator mode, you cannot sprint by double tapping W or using a Sprint key. The hunger bar should not affect your ability to sprint, the same way it doesn't affect you in Creative mode.
Steps to reproduce:
Create a new world.
Switch to spectator.
Start sprint.
Switch to survival.
Give yourself the hunger effect and wait until you have 3 bars or less.
Switch to spectator.
Start sprint.
Observed results:
Player cannot sprint in Spectator mode when on low hunger.
Expected results:
Player can sprint in Spectator mode when on low hunger.