Say no to packaged food
Anything that came from trees, vines, bushes, and other types of plants should be good enough. Memorize the grocery lanes that lead to the vegetables and fruits section. Forget where the food packaged in bags or boxes are located. They mostly contain preservatives, additives and other stuff. Check the ingredient list, as well. Make sure you can read them all. They should not exceed six ingredients, too. If it is more than that, then, it is processed food.