Jeremy is a 25-year-old man training for an ultramarathon race
of 50 miles. He is 5 feet, 10 inches tall and currently weighs 170
lb. During his long runs of more than 3 hours, he drinks water,
approximately 30 oz., and consumes one GU (an energy supplement
containing 100 kcal from simple sugar) at the 2-hour mark. Jeremy
is coming to you for advice because he is becoming increasingly
weak and nauseated toward the end of his runs. He reports...