In this guide, you will find how never to need to eat again in The Sims 4. You have to buy a Reward trait to do so.
Your sims will get hungry and need something to eat after some time in the game. The hunger bar will also decrease with time. You can buy a reward trait that will stabilize your hunger bar; you will need 10,000 satisfaction points to buy it.
So tap the Rewards Store button, and scroll down to Forever Full reward. You need to buy it.
After that, your hunger will stay stable and it will never decrease.