Life in the U.S. for Immigrants: Can long-distance running help you lose weight? Research by American exercise physiologist Mary Kennedy shows that one should not rely on this exercise to reduce body weight; however, people should not have made weight loss the primary goal of long-distance running in the first place.
Kennedy recruited 64 marathon enthusiasts to run 4 days a week. After 3 months, it was found that 78% of the volunteers' weight remained almost the same, 11% lost weight, and another 11% gained weight; 86% of this latter group were women.
Kennedy told New York Magazine that weight gain after long-distance running might be due to increased appetite and higher calorie intake, as people "may eat more without realizing it." Additionally, she said, some beginners may wrongly assume that they need to replace calories after intense training, "but this does not mean you should eat a big plate of pasta followed by 4 slices of bread."
Kennedy remarked that while long-distance running has many health benefits, many people are only concerned with whether it can help them lose weight.