Because foods low in fiber tend to sit in the gut for longer, they can cause a buildup of excess water and fluids in the body. An individual's level of hydration does not only depend on the amount of water they drink throughout the day, but also on the types of food the individual consumes. While sufficient hydration is key, when the body retains excess fluid because of elements such as the lack of fiber, it is not particularly comfortable or healthy. Frequent bloating, a feeling of swelling in the belly, is a sure sign one's diet does not contain enough fiber. Diets rich in fiber allow the body to expel wastes such as fluids much more quickly, ensuring individuals do not get bloated.