Q: The Paleo diet emphasizes foods our early ancestors evolved to eat—namely lean meat, fish, fruits, veggies and nuts, but no grains. What do you think of it?
A: The notion that we should return to early-human eating habits resurfaces regularly. In recent years The Paleo Diet and other books have promoted it. They rely on a form of evolutionary or genetic determinism, claiming that humans were “designed to eat” lots of meat and that we’re overweight and develop chronic diseases because we’ve strayed from this ideal diet.
Paleolithic proponents assume that early humans were hunter-gatherers who depended almost exclusively on lean meat and raw fruits and vegetables, seldom ate cereal grains and had no dairy products. They speculate that early humans consumed much more animal protein than we do, no refined sugars, more fiber and much less sodium.
However, evidence about early diets is very fragmentary. Any theory of an “average Paleolithic diet” is problematic: this period lasted many millennia, and early humans lived in ecological niches with widely varying food sources. They ate whatever they could kill or lay their hands on.
Few of our Paleolithic forebears had heart disease or cancer—but that was because they rarely lived long enough to develop such chronic disorders. Many, undoubtedly, suffered from nutrient-deficiency diseases and starvation.
Paleo diet plans do have some good aspects. They rule out junk foods and added sugars, and cut way down on salt. They emphasize nutrient-rich, high-fiber fruits, vegetables and nuts. But they also rule out some healthy foods, such as whole grains, dairy products and beans.
You don't need some hypothetical Stone Age ancestors to justify common sense advice to cut down on highly processed and sugary foods. Yes, you're better off eating four ounces of lean meat than a four-ounce danish. But foraging for a carrot or berries would be best of all.