Natalie Digate Muth by Natalie Digate Muth

Paleo DietFollowers of the Paleolithic Diet—commonly referred to as the Paleo Diet, the Caveman Diet and Stone Age Diet—adopt an eating plan intended to mimic what hunters and gatherers ate in the Paleolithic period more than 10,000 ago, before the advent of agriculture: whole fruits and vegetables, fish, grass-fed livestock, fungi, roots and nuts. The diet prohibits grains, legumes, dairy products, salt, refined sugar and all processed foods. The basic premise of the Paleo eating plan—that we should be eating more “real” foods—is easy to support. 

Of course, it is impossible to perfectly mimic a caveman diet—after all, not many of us hunt our own wild game, eat only wildly grown organic foods or grass-fed meats, catch our own fish or spend the entire day running around in search of food. The reality is that, in our current food environment, many people would have a hard time completely eliminating the huge amount of widely available processed food items for the long haul.

At first glance, however, the Paleo Diet looks pretty healthy. Who can argue with eating a wholesome diet of foods that you not only know the location of where they were grown or raised, but can also understand every word on the ingredient list? In fact, a diet rich in fruits and vegetables, fish and nuts looks remarkably similar to a Mediterranean diet, which a considerable amount of research has identified as among the healthiest diets in the world.  

The problem comes with other aspects of the Paleo diet; specifically, an absence of grains and dairy products, and the emphasis on meat. After all, studies have demonstrated the benefits of whole grains, legumes and low-fat dairy. And we know that too much red meat is linked to heart disease. Due to the lack of dairy products, calcium and vitamin D intake can be particularly low on this eating plan, which can be harmful to bone health. The diet also tends to be very low in carbohydrates, which could contribute to suboptimal performance for athletes. However, it is worth nothing that a Paleo eating plan can be adapted to avoid nutrient deficiencies or support an active lifestyle, but the average person will likely struggle.

Overall, there is a lack of quality scientific research evaluating the merits and limitations of the Paleo Diet. A scientific search of peer-reviewed research studies on Paleo comes up shockingly short, with just a few small and short-lived studies evaluating its benefits and risks. However, a panel of expert reviewers tasked with ranking 29 diets for U.S. News & World Report placed the Paleo Diet at the bottom, with just 2 out of 5 stars. A wide range of variables were measured, including the overall quality of the diet, short- and long-term weight-loss benefits, how easy it is to follow, nutrition, safety, for diabetes and for heart health. The diet got a sobering 2 stars for each category. The pros? It works for meat eaters and is very low in sodium. The cons? It lacks grains and dairy products, has a high overall fat content and a high price tag. Followers of the Paleo diet published a full rebuttal to the U.S. News study, arguing for the benefits of a Paleo-type eating plan. It is prudent to note some of their arguments. For instance, if Paleo followers emphasize omega-3 fatty acids (and not all types of fats); consume a wide variety of vegetables and fruits; eat only healthy meats (as the plan advises) and avoid the processed salami, bologna, bacon and sausage; and accept that they may not get recommended amounts of calcium or vitamin D (and consequently take a vitamin D and calcium supplement), then they should do well on this plan.

Check out Ask an ACE Expert to find out what other registered dietitians have to say about the Paleo Diet.