Hi, Im 15, and i've started noticing that my friend has been complaining a lot about symptoms that suggest low blood sugar. Frequently when doing any exercise, he becomes nauseous, or dizzy. A couple of times he has had to get some kind of sugar filled snack during breaks, just to feel better. Just yesterday he told me that he fell of of his bike when biking to school in a sudden bout of dizzyness. I know that when i exercise in the morning (i bike a few miles to school everyday, and go running periodically) i sometimes feel sick, but not that drastically, and thats only if im really really pushing myself. I know that he's less fit than me, and has been trying to do a lot of workouts to get in shape. He's fairly skinny, and eats a ton, yet doesnt gain that much weight. What could these symptoms mean? (they have only just started in the past couple weeks).