What Are Trans Fats? Nutrition Trans fats are created when liquid oils are I transformed into solids through a process called hydrogenation.Trans fats are prevalent in many processed foods because they add to a product's shelf life and increase flavor stability.Most of the foods that contain trans fats should be eaten in moderation anyway-even if they didn't contain trans fats.Trans fats are often found in deep-fried restaurant foods, as well as in doughnuts, cookies, cakes and muffins. Want to Keep Reading? Continue reading with a Health Confidential membership. Sign up now Already have an account? Sign in