Glycemic Index Simply Put The majority of carbohydrates consumed should be low glycemic because they take longer to digest. Therefore, energy is released at a slower rate taking a longer period of time. Weight management assists in controlling insulin levels and contributes to longer endurance performance. High glycemic foods should be limited. Quick spikes in sugar from many high glycemic processed sources, such as white bread, candy, and soda that are not used up immediately, are easily stored as fat.