While the Paleo Diet and other ancestral-type diets allow meat and fish consumption, they are more restrictive than the typical vegetarian diet because they don’t permit grains to be eaten, and grain-based foods are in fact the most abundantly eaten foods in the modern diet. Dairy products are also forbidden in ancestral diets, on the grounds that, like grains, our Paleolithic ancestors did not eat them. (Too bad this isn’t true. Recent evidence suggests some humans ate grains as long as 100,000 years ago.)
Is the Paleo Diet healthier than a simple “high-quality” diet in which no food types are forbidden, only “low-quality” foods of each type (e.g. processed grains vs. whole grains)? No. For example, a recent study out of the Harvard School of Public Health found that men and women who ate more than two servings of brown rice per week had a lower-than-average risk for type 2 diabetes, while those who ate five or more servings of white rice per week had an above-average risk for the disease.
In other words, whole grains are better than none at all. Other research suggests that, similarly, eating low-fat dairy products is better than eating none at all.