Running and Eating
True or false: The more you run, the more you eat. Answer: True sometimes and false other times. It would seem obvious to everyone that the more active you are, the more calories you will burn. The first doubt of this came in a2012 study of modern hunter gathers. Although these tribesmen were very active all day long, it was discovered that they were not using nearly as many calories as expected. Somehow, their bodies found a way to get more activity with less food.
The 2012 study prompted a group to conduct a more detailed study into the same topic. A race across America was scheduled to start in California and end in Washington DC. Participants would run about a full marathon a day for 20 weeks. Six agreed to be studied.
Before the race began, resting metabolic rates were measured using sophisticated methods involving isotopes. During the first week, the runners were tested daily and found to be burning 6200 calories a day. This is about what would be expected. It is three and a half times more than their resting base rate. No surprise here.
The big revelation came during the last week of the race, when they were tested again. Although they were running the same distance each day at the same pace, they were now burning fewer calories than five months ago when the journey began. Instead of three and a half times more than resting rate, they had cut it to two and a half times resting rate. Somehow, they were doing the same work but using fewer calories. In addition, most of the runners had not lost weight.
Less rigorous studies of other long, grueling physical endeavors such as the Tour de France, Artic expeditions and ultra-marathons have pointed in the same direction. The bottom line conclusion is that whenever a strenuous event lasts over 12 hours, energy expenditure initially increases greatly and then starts to decline. The boundary lines are always about the same: 3.5 times resting rate and then declining to a maintainable 2.5. How the body manages to pull off this stunning transformation is still a mystery. One more reason to marvel at the wonders of nature and the amazing body.