The physiological role of fiber in the human diet is multifaceted. It aids in digestion by promoting regular bowel movements and preventing constipation. Fiber can also help regulate blood sugar levels by slowing down glucose absorption and lowering cholesterol levels by binding to fats in the digestive system. Additionally, fiber contributes to a feeling of fullness, which can help in weight management. Overall, it supports gut health and can reduce the risk of chronic diseases.