Your afternoon headaches after morning runs could be due to mild dehydration or electrolyte depletion, as fruit alone may not replace all the sodium and potassium lost through sweat. Another common cause is a primary exertional headache, often triggered by blood vessel changes during exercise. To help prevent this, try drinking water with electrolytes before and during your run. Adding a complex carbohydrate and protein snack (like whole-grain toast with peanut butter) can also stabilize your blood sugar better than fruit alone. Remember to warm up and cool down gradually. If these headaches persist, please consult your doctor.