Is there a way to make it so hunger doesnt go down?

Solution 1:

If you have access to commands, you can use

/effect [username or @a (for all players)] 23 99999 10

Effect number 23 is the effect for saturation. It will replenish your hunger bar. With the power of it being set to 10, it will regenerate half of the whole hunger bar per tick (you can raise it to 20 for the entire bar at a time).

To refresh it, you just need to type in the command again. If you use Command Blocks, you could easily set up a button to do it (if you have access to commands).

Solution 2:

You can set up a separate launcher profile to play on a version previous to Beta 1.8, (which is when the Hunger Mechanic was added).

Failing this, you may need to install a custom mod. Doing a quick search for disabling hunger in Minecraft turned up a couple of options such as this one:

I've never used them so I cannot tell you how well they work, you will need to test them yourself.