Fast carbs are foods that contain a high glycemic index, while slow carbs are foods that have a lower glycemic index, states SFGate. A food's glycemic index determines how quickly carbohydrates elevate blood sugar in the bloodstream after they are absorbed. Higher values mean quicker absorption.
Examples of fast carbs include bread, cereals, sugars, fruits and a number of starchy vegetables, according to SFGate. As the individual carbohydrate molecules are smaller in fast carbs, they are processed more efficiently and quickly by the digestive system. A diet that is overly reliant on fast carbs exposes the individual to heightened risks of Type 2 diabetes, cardiovascular disease, weight gain and metabolic syndrome. Although questionable if used as a dietary staple, fast carbs are useful for quickly recovering energy following exercise. This is because they restore depleted glycogen reserves in the liver and muscles.
Most vegetables, whole grains, seeds, nuts, beans, peas and legumes are examples of slow carbs, notes SFGate. These foods typically contain higher levels of fiber as well. Although slow carbs are processed less quickly than fast carbs, they are more proficient at providing energy to the body over an extended period of time. This also means that slow carbs do not cause sudden spikes in blood sugar levels. Consuming slow carbs instead of fast carbs can lessen hunger.