Running long runs without fuel isn’t helping your performance — it’s limiting it. Once you pass about 60–90 minutes, your body’s stored glycogen begins to drop, and relying solely on fat becomes too slow to support steady endurance work. According to the American College of Sports Medicine, consuming carbohydrates during longer sessions helps maintain blood glucose, sustain pace, and delay fatigue. Research from the Journal of the International Society of Sports Nutrition also shows that trainin