Our expanding waistlines result from the competition between our modern diet and our ancestral genes. The book Newton’s Football (Random House) spells in out:
Cheap and easy access to calories is a very recent development in the human condition. The hunting and gathering that early man did was a boom-or-bust business. One day there’d be a feast in the form of ripe fruits and vegetables or a freshly killed ox. And there were, of course, no Ziploc bags or Sub-Zero refrigerators in which to store the leftovers.
When the harvest was over and the hunters hit a dry spell, it was famine time. Attempts to store food were generally unsuccessful, and even when it did work, it still required an early human to defend the food against those who’d steal it, human or otherwise.
Storing excess calories as fat was an elegant solution to these problems.
“Fat is the best defense against a rainy day, and throughout human history there were lots of rainy days,” explains David Katz, founding director of the Yale Prevention Research Center.
Additionally, there is a new ingredient in our diet that our ancestors rarely enjoyed, and that is processed sugar. Sugar is surprisingly prevalent in our modern diets and is found in bread and crackers and salad dressing and tomato sauce. And, that’s more calories to burn.
Sugar in moderation is a good thing and serves as a fuel for our bodies, but if we don’t use sugar, it gets stored. “It’s subject to the laws of thermodynamics,” says Katz. “If you don’t burn it, the body will store it as an excess of calories.”
As one can see, fat was a Stone Age solution for a rainy day when there wasn’t any food. Unfortunately, in our modern day, that rainy day never comes.
So, blame those extra pounds on your ancestors.