I learned about energy efficiency in a very painful and embarrassing way. Many years ago, I entered the famous Western States 100-Mile Endurance Run, which follows tortuous old gold-miners’ trails over the Sierra Nevada Mountains. I had calculated that I’d burn about 130 calories per mile, which meant I’d need about 13,000 calories to get through that run. So, I planned to consume about 80 PowerBars along the way. The first few hours went easily enough, but by the time I reached a major aid station at 54 miles, I was deathly sick and severely dehydrated — yet could no longer stand the sight of either food or water. How on earth were the other runners able to keep going? Only later did I learn that evolution has created a kind of bodily ecology that with training enables very small amounts of carbohydrate to interact with small amounts of fat to generate a far more efficient propulsion than I’d thought possible. Energy efficiency, it turned out, was a far bigger factor than energy supply in determining a man or woman’s ability to run over rough terrain all day and all night.
As I lat... Read more