The Truth About the Paleo Diet

By , Kamal Patel, Director of
If you've been in touch with diet trends over the past few years, chances are that you've heard of the Paleo diet. When you Google the word "Paleo" or "Paleo diet," you'll find thousands of blogs, recipes, articles and best-selling nutrition books. But what exactly is Paleo—and is its popularity warranted? Is it all hype and marketing, or is this truly the best diet to adopt for optimal human health? Let's take a look at what the evidence says. 
First, what exactly is the Paleo diet?
This is a tough question, believe it or not. The Paleo diet is more of a concept than a precise, regimented plan; some would even go so far as to say that it is a lifestyle rather than a diet. Furthermore, no one person is responsible for actually developing the Paleo diet (although the term ''The Paleo Diet'' is actually copyrighted by seminal researcher Loren Cordain), and there are many different interpretations of what is and is not Paleo.
With that being said, here is the most basic tenet of Paleo in a nutshell: Throughout the process of evolution, we humans gravitated toward foods that helped us survive, while avoiding harmful foods that were poisonous or ill-suited for our physiology. Through a process of evolutionary trial and error, our ancestors eventually became well-adapted to eating certain foods. The Paleo diet posits that modern-day humans have not yet adapted to the foods that came from the agricultural revolution, like grains, dairy and refined sugars. Paleo supporters claim that by eating the whole, minimally-processed foods of our Paleolithic ancestors, we can lose weight, gain more energy, and even reverse common modern lifestyle diseases.
So, what can you eat on the Paleo diet?
In general, Paleo-eaters advocate a diet heavy in foods that our ancestors would have been able to hunt or forage. This means that vegetables, meat and seafood, eggs, fruits, nuts and seeds are encouraged, while grains, dairy, legumes, soy, added sugar and other processed foods are avoided. The Paleo diet does not recommend counting any calories and/or macronutrients as much as some other diets do; just as our ancestors did, you simply eat until you are satisfied.
No whole grains, dairy products, or beans? But I thought these foods were healthy!
Okay, so the elimination of added sugars and processed foods makes sense; a perpetually-growing body of research has shown that these foods contribute to obesity, diabetes and heart disease. But wait! What's wrong with whole grains, dairy and beans? Dietitians and FDA guidelines have been telling us for years that we should eat multiple servings of these foods per day. Are these seemingly wholesome staples of our diet really that unhealthy?
This is where Paleo logic can get a little shaky. Humans are crafty omnivores who can thrive on many different types of foods, so pinpointing exactly what we should eat for optimal health is a difficult task. It's true that food intolerances do exist, but not all post-agricultural foods are harmful for everyone. Although dairy and beans weren’t eaten much in Paleolithic times, these foods haven’t caused many adverse health effects in studies (and have actually shown health benefits). Therefore, although the Paleo diet recommends against post-agricultural foods, many people tailor the diet based on their individual food reactions and personal health goals.
Does the Paleo diet actually work? What do the studies say?
Followers of the Paleo diet claim that eating like a caveman can reverse chronic diseases, improve sleep, clear up skin, increase energy, spur weight loss, and boost the immune system, among other benefits. However, there has not been much research to support these claims, and the evidence is mainly anecdotal. There have only been a handful of direct studies on the effects of the diet. Before summarizing these studies, it’s important to note that publication bias is rampant in diet and nutrition studies. Studies showing positive results get published more often, and study authors often have a vested interest in the nutrient or diet they are studying. Plus, diet studies are often too short to assess long-term effects and diet compliance. Of the published Paleo studies that have been completed, some lasted just a couple weeks and none went over 12 weeks. That being said, the study results we have to work with are very positive so far.
Since we can currently count the number of completed Paleo studies on one hand, let’s quickly review each one. The first, from 2007, showed a Paleo diet to reduce waist circumference and improve glycemic control better than the Mediterranean diet. Another comparative study in 2009 showed that a Paleo diet reduced cardiovascular risk factors in patients with diabetes more effectively than other diet protocols.

The other three studies did not include a comparison group, so the evidence isn’t as strong since improvements can happen just from adopting a new diet. With that said, these study results were all positive, showing that adopting a Paleo diet led to a reduction in blood pressure, fasting blood sugar, and some markers of heart disease.

Despite the excellent results, we cannot reasonably conclude that a Paleo diet was the sole reason for the health improvements in these particular studies. When you adopt a Paleo diet, you tend to lower both your calorie and carb intake while increasing your protein intake. This often happens because there are fewer food options available to you on a Paleo diet. You can’t grab a bag of chips, a cookie, or a sugary drink at Starbucks. Instead, your options are narrowed down to fruits, nuts, raw veggies, or one of a few other options that don’t exactly encourage overeating.
It's possible that any other diet that reduced calories and sugar would have worked just as well as a Paleo diet in these studies, but there is not enough evidence to say just yet. Despite their small scope, the existing Paleo diet studies are a good starting point, and will hopefully spur longer-term studies with a variety of different comparison groups for more robust and definitive results.
What's the bottom line? Should I try eating like a caveman?
When you look past the details to the big picture, the Paleo diet focuses on eating high-quality foods until you are satisfied. One thing you can't argue is that focusing on eating whole, unprocessed foods is a good way to start eating healthier. But this isn't a new concept. People have been eating natural foods for millennia; they just didn't slap a Paleo label on their way of eating. I quickly learned this after explaining the concept of Paleo to a fellow nutrition researcher from Nigeria, who just laughed at silly Americans and their diets while eating her hearty (Paleo?) Nigerian stew.

It’s less important to know whether something is ''Paleo'' than it is to know how it affects your particular body and supports your health goals. If eating a Paleo diet helps you eat more of the good stuff while eliminating excess sugar and processed foods from your diet, then by all means, go for it! Just remember that while it’s important to have a diet rich in nutrients, there are many ways to get to old age, and few foods are absolutely necessary, and even fewer are absolutely going to kill you.
There have been thousands of trials conducted on different nutrients, foods, and ways of eating. You can pick and choose among these studies to support a variety of different diets. But the best diet for one person is not the best diet for everyone. So the next time someone touts Paleo as being a cure-all, take their advice with several grains of salt. While there isn’t much direct evidence for Paleo, the few studies show promise and basing a diet on natural foods is a wise move. Just don’t get caught up in the hype.

Editor's Note: Looking for some paleo recipes? Check out our "Practical Paleo" resources at
Frassetto, L.A., Schloetter, M., Mietus-Snyder, M., Morris, R.C. Jr., Sebastian, A. "Metabolic and physiologic improvements from consuming a Paleolithic, hunter-gatherer type diet," European Journal of Clinical Nutrition.
Jonsson, T., Granfeldt, Y., Ahren, B., Branell, U.C., Palsson, G., Hansson, A., Soderstrom, M., Lindeberg, S. "Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study," Cardiovascular Diabetology.
Lindeberg, S., Jonsson, T., Granfeldt, Y., Borgstrand, E., Soffman, J., Sjostrom, K., Ahren, B. "A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease," Diabetologia.
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About the Author
Kamal Patel is the director of He has an MBA and an MPH (Master of Public Health) from Johns Hopkins University, and was pursuing his PhD in nutrition when he opted to go on hiatus to join He is dedicated in making scientific research in nutrition and supplementation accessible to everyone. Both and Kamal are on Facebook.