Liquid energy with portable and fast-absorbing carbohydrates, this great tasting energy source also includes electrolytes for optimal hydration, amino acids to reduce muscle breakdown and caffeine in some flavours for increased focus. GU limited consumption to 100 calories because, in general, the body can digest roughly 350 calories per hour during exercise. If you tried to eat more, the body would divert blood from your muscles— say “buh-bye” to a personal record—to handle the excess food. If your metabolism is slow, then one GU every 45 minutes works fine. If you have an athlete’s metabolism, try ingesting one every 30 minutes and see if it agrees with you.