A sports nutritionist advises athletes on nutritional regimes that will allow for optimal performance and must understand the effects that foods have on the human body. Those who work in sports nutrition study not only what types and quantities of foods and fluids should be consumed by an athlete but also the particular organic substances that are most important for athletes competing in a given sport. Sports nutritionists must develop eating regimes for athletes that properly balance the athlete’s intake of substances such as carbohydrates, proteins, and fats. Nutrition is of vital importance for athletes in strength sports and in endurance sports like running and swimming.