Fiber is a type of carbohydrate that cannot be digested by humans. It comes in two forms: soluble (dissolves in water) and insoluble (does not dissolve in water). Both have unique benefits to our health, and both are generally found in plant based foods such as vegetables, legumes, beans, and whole grains.
Often, low carbohydrate, high protein diets, tend to be deficient in fiber (20-30 grams/day is the recommended daily allowance). In addition, diets high in processed foods also tend to be deficient in fiber (this is due to processed foods having a longer shelf-life with the fiber removed). Also consider using a fiber supplement as necessary to ensure adequate daily requirements are met.