The "paleo diet," which has become popular over the past year or so mainly through books, the Internet and social media buzz, is based on a premise that eating like our hunter-gatherer ancestors in the Paleolithic period will help us lose weight and live longer, while minimizing heart disease and Type 2 diabetes.
It is partly based on a theory that today's highly processed, grain-focused food choices are to blame for many of our chronic diseases. The diet calls for eating meat, fish, poultry, eggs, nuts, seeds, vegetables and fruits while avoiding grains, dairy foods, legumes (beans and peas), processed foods and those containing refined sugars.
Does it work? It's too new for the few studies done so far to be conclusive. However, nutritionists have their doubts.
"If you search for controlled studies on the paleo diet -- meaning it was tested against another diet -- you'll find a couple of short-term studies, each done with a relatively small number of people," says Brie Turner-McGrievy, an assistant professor and registered dietitian in health promotion, education and behavior at the University of South Carolina. Like many diet studies, these show slightly more weight loss and some improvement in chronic disease indicators for the paleo plan. But a few short-term studies don't constitute a dependable evidence base.
In U.S. News and World Report's 2014 ranking of Best Diets Overall (compiled with the help of top health and nutrition experts), paleo tied for last in a group of 32 diets, with this comment: "Experts took issue with the diet on every measure. Regardless of the goal -- weight loss, heart health or finding a diet that's easy to follow -- most experts concluded that it would be better for dieters to look elsewhere." The magazine's No. 1 diet was the government-developed DASH (Dietary Approaches to Stop Hypertension) diet.
Paleo advocates recommend eating meat and avoiding all grains, saying the grains we eat today have been dramatically changed with modern agricultural techniques. One problem they cite is greater gluten content.
"The notion that our ancestors ate more meat than grains is not based in fact," says Julie Miller Jones, a professor emeritus in nutrition at St. Catherine University in St. Paul, Minn., who has studied grains extensively. Our ancestors were constantly gathering grain-based foods," she adds. "Though the hunt for meat was pretty constant, the kill was rare. They didn't sit down to Tyrannosaurus steaks every day."
As for the gluten assertion, Jones points to research sampling century-old wheat showing that the amount of gluten hasn't changed. But she acknowledges a small increase in the population of people with gluten sensitivity and celiac disease, as well as other autoimmune diseases, such as Type 1 diabetes.
"A lot has changed in our environment. Perhaps it's changes in our grains, the gut, use of antibiotics or countless other factors," Jones says.
Jones also says it's "absolutely not" a good idea to avoid eating all grains. "We need a variety of whole grains, as well as legumes, fruits and vegetables, to get the gamut of dietary fibers for their unique effects on the heart, digestive system and insulin and glucose control." She adds that grains' and legumes' different types of fibers and amino acids make them a perfect nutritional match for the body's needs.
Eliminating whole grains and legumes might leave people deficient in iron and zinc and some B vitamins. Deleting dairy could make getting enough potassium a challenge. And going heavy on animal-based proteins, which take center stage in the paleo diet, could raise saturated fat and cholesterol intake.
Research shows most people can follow a regimented eating plan for a short time. That's not the challenge. The challenge is finding a healthful eating plan you can follow day after day and achieve your long-term health goals.
At this point, it doesn't appear the paleo eating plan meets these objectives for most people.
Hope Warshaw is a registered dietitian nutritionist and certified diabetes educator.