Dietary fibers are even longer chains of complex carbohydrates. Unlike starch molecules, these fibers resist digestion because of their chemical configurations. Therefore, most fibers eventually end up in the colon and form the bulk of your stool. Most people think that fibers are only the husks of grains and the long stringy components in fruits and vegetables, but actually, dietary fibers are present in all plant tissues. For example, after a potato is peeled, the white matter we eat has plenty of relatively indigestible fibers in it.
Fats too are complex molecules made up of carbon, oxygen, and hydrogen.
Although they are not as easily digested as sugars are, fats are sources of energy and they provide important structural materials for building different components of the human body. Most fats can be synthesized by our own bodies from carbohydrates as they are needed. The fats that we can synthesize are said to be nonessential because they are not necessary ingredients in our diet. The only fats we cannot synthesize for ourselves are a few unsaturated fats. They must be provided to us, ready-made, in our foods and therefore are called essential fats.