Quite a few features have changed in Horizon Forbidden West, including the way that you handle food. One thing you will notice is that cooking isn't the same as in the prequel. This means that you need to learn how to get food in Horizon Forbidden West to get its helpful buffs.
Overall, cooking food is not worth it due to the length of the buffs being mediocre. By the time you've eaten and traveled to the place you need to go, it'll no doubt already have run out, or just about.
To get food, you will need to purchase it from the various Cooks that can be found in some settlements around the map. You aren't going to be cooking for yourself in this game. In addition, the food you can buy will change based on the location you are currently at.
You will need to exchange items that you find in the wild for food. Several plants like Riverbloom are exclusively used to exchange for several dishes. You can see the dish purchasing requirement in the Cooks menu, as well as what the dish helps with.
Purchased food will be added to your Hunter's Kit, and can be consumed like healing items. Food that has stronger buffs will cost more, while basic dishes will only cost you basic items.
For more Horizon: Forbidden West guides, check out How to level up quickly in Horizon Forbidden West on Pro Game Guides.