Lately, nutrition experts have been saying that we should eat like people used to. They don’t mean before microwave ovens, but rather like our ancestors did 10,000 of years ago. In those days, the main problem with food was not over-consumption as it is today, but rather finding enough to prevent starvation. Our evolutionary ancestors solved this problem by storing fat quickly and easily to see them through periods of famine. “Back then,” quips weight-loss expert Dean Ornish, M.D., president of the Preventive Medicine Research Institute in Sausalito, California, “it was survival of the fattest.”
Today, we have essentially the same genetic makeup as our starvation-threatened ancestors, but the very fat-storage mechanism that saved them is killing us. According to anthropologists S. Eaton Boyd, Ph.D., Marjorie Shostak, Ph.D., and Melvin Konner, M.D., Ph.D., authors of The Paleolithic Prescription, we’ve become caught in a dietary time warp. Like Rip Van Winkle, we’ve awakened in a world of high-fat McFoods that our bodies are genetically incapable of thriving on. The results? All the fat-related chronic illnesses that have become our leading causes of death.
How should we eat? Like our Stone Age genetic ancestors. Dr. Boyd is an expert on ancient diets, and Drs. Shostak and Konner lived for several years with the Kung tribe of the Kalahari Desert in southern Africa, one of the few remaining hunter-gatherer peoples on earth. Together they pieced together what early humans ate, primarily plants–nuts, fruits, beans, grains, and roots–with some game meats. But those meats were much different from ours. They contained only about 5 percent fat by weight, much less than our domesticated meat animals (30 percent fat). Overall, these experts contend, the human body evolved to consume no more than about 20 percent of calories from fat, only about half of what most Americans eat today.
Throughout the vast majority of human history, even after the arrival of civilization, agriculture, and industry, people continued to eat more or less as they were genetically programmed to do. In 1910, Americans ate a diet based on carbohydrates, with only about 20 percent of calories from fat. “They consumed more total calories than we do today,” says Neil Barnard, M.D., author of Food for Life and president of the Physicians Committee for Responsible Medicine in Washington, D.C., a professional organization that promotes preventive medicine through nutrition, “but far fewer from fat, and heart disease, cancer, diabetes, hypertension, and obesity were all rare.” Today, according to a recent report by the National Center for Health Statistics, American fat consumption averages 34 percent of total calories. That average is down slightly from 1978, when the figure was 36 percent, but averages can be misleading. Some Americans have cut way back on fats, but millions still consume at least twice as much fat as their great-grandparents did.