As a marathoner, you'll burn through lots of energy on the 26.2 mile course. Because nutritional needs and energy demands are high, runners should strive for balanced, nutritious diets in order to improve performance and endurance.
The number of calories you burn while running a marathon will depend on a number of factors. Male runners, for example, typically require more energy for physical exertion than their female counterparts. Age is also a major factor -- older runners typically have a slower resting metabolic rate. Lastly, body weight plays a role in calorie burning. For example, as a runner you'll burn more calories if you're 210 lb. than if you weigh 125 lb.
Estimated Calories Burned
According to the Cleveland Clinic Center for Consumer Health, a runner who weighs 130 lb. will burn 2,224 calories during a marathon, a 165 lb. runner will burn 2,822 calories and a 210 lb. runner will burn 3,593 calories.
While exercise and physical training are important aspects of marathon running, nutrition is also a key factor. You should have an adequate balance of energy intake and output and strive for balance and variety in the foods you eat. Running Planet says that a typical marathoner's diet is around 65 percent carbohydrate, 25 percent protein and 10 percent fat.