There is a hidden meter called saturation which has to empty before hunger starts going down. It's refilled by eating, though by how much depends on the food and is not related to how much hunger it fills. Pro tip: golden food is the best in terms of saturation.

How

Assuming you're okay with using command blocks you can kinda set up a trap like this:
Type this in the chat while in-game on any opped account:

/give @s repeating_command_block

Now type this:

/gamerule commandblockoutput false

You must be in creative mode.
Then you can put a bait chest down, maybe put diamond or something in it.
Place the command block a few blocks below the chest and put this command into the input field:

tag @a[r=20] add sus

Then on the left there will be a select bar that says "Needs Redstone". Click on it and select "Always Active".

Now you can always type this in the chat window:

/testfor @a[tag=sus]

Now anyone who entered the area who is online will appear in chat. This will be permanently attached to them unless you were to manually remove it.

Notes

• Of course not everyone who enters the area is nefarious, so make sure to put it somewhere it is obvious you are not allowed to go
• Everyone will appear, so your kids and you included. Obviously you can ignore yourself.
• Only people online will appear, however once they rejoin the game will still remember, so it will be permanently attached to them.
• Don't fret! Other players will not be able to pull up the GUI you used to make this system, and they cannot break the block either.

Cons/Solutions

• Only people online will appear, you can use Universal Minecraft Editor if you send a world to the Mac, but I will not go over how to do that as that is rather complicated and I am not sure how to look through someone's tags.