Diet Talk: Everything you need to know about Complex Carbohydrates Complex Carbs are one the most talked about type of carbs in the fitness world, if you didn’t know. They are composed of multiple chain-linked carbons molecules that the body has to break down in order to use it for energy. They are also packed with vitamins, minerals, and fiber; unlike simple sugars. Simple sugars contain no nutritional value AT ALL, but they fucking taste good! The majority of your carbohydrate intake should be complex carbs, at least 75–80%+.