“Fiber is the non-digestible part of carbohydrates,” says weight loss dietitian Lauren Hubert, M.S., R.D. Whole carbs (fruits, veggies, legumes, and whole grains) all naturally contain some fiber. While sugars from these foods are broken down and absorbed into the bloodstream as glucose, fiber makes it through the digestive tract relatively unscathed.
Fiber is mainly split into two categories: soluble and insoluble. Soluble fiber dissolves in water to form a gel-like substance in the gut. Its stickiness slows down digestion and traps and removes unwanted substances like cholesterol and environmental toxins from the body. Insoluble fiber, on the other hand, adds “bulk” to stools and helps keep things moving.
Most foods contain a mixture of both types of fiber.
