Bonk is the body running out of fuel, it has burned everything that it can and shutsdown until it can convert fat (or muscle) into fuel.

Bonk is a temporary thing...at least it is if you can sit on the side of the road and eat something, anything to replenish.

Heat exhaustion is something else entirely, but with similar first sysmptomys (SP).

Can someone more educated than me, help on this?