One explanation is tied to the fact that "men will burn a greater percentage of carbohydrates for fuel than women," a researcher tells the New York Times. Women burn more fat, and people have more fat than stored carbohydrates in our bodies. The result: "Men typically run out of fuel and bonk or hit the wall earlier than women do." Then there's the fact that men use a "risky" running strategy. "They start out fast and just hope they can hold on," the researcher says.