Before 2010, the paleo diet was virtually unheard of. But within three years, the word paleo has become common knowledge, enthusiastically celebrated on menus and grocery store items. New restaurants opened with a focus on the grain-free, dairy-free diet; the Crossfit athletes started touting the benefits of their hard-boiled eggs, salmon fillets, and handfuls of almonds. Paleo had officially taken over.
According to Google Trends—which tracks the popularity of words over time—paleo diet peaked in January 2013, but Americans’ interest in it spikes again each January (you know, because of those New Year’s resolutions).
It’s clear the paleo diet continues to lure health-conscious folks in, so let’s dish on what this stone age diet really is.
What a Paleo Diet Actually Means
A paleo diet (or Paleolithic diet) can be boiled down to four words: “Eat like a caveman.” The theory behind the paleo diet is that humans have strayed too far from their natural historical diet—the one they were genetically predisposed to eat.
Proponents of the paleo diet might argue that the hunters and gatherers from the Paleolithic years would likely not even recognize today’s cheese puffs and toaster pastries as food. Those who follow the paleo diet believe these processed, grain-centric foods—cereal and pizza and bread—might be behind some of our modern illnesses, such as heart disease, type 2 diabetes, and certain cancers.
In short, paleo dieters wish to turn back the clock and return to these simpler culinary times, prior to the agricultural revolution.
What to Eat on the Paleo Diet
In a nutshell, the paleo diet consists of food you could theoretically hunt or gather. (It doesn’t actually mean you have to go out and hunt or gather your food yourself, unless putting items into a grocery basket counts as “gathering.”)
“Hunted” foods include animal proteins, such as beef, chicken, turkey, fish, or seafood. The paleo diet prefers meats that are grass-fed, organic, wild-caught, etc. (though this is not required). In other words, you want to source foods that use traditional methods for raising or feeding livestock.
“Gathered” foods include eggs, nuts and seeds, and fruits and vegetables. When possible, organic and local produce is preferred.
Minimally processed foods are allowed, such as almond milk, jerky, crackers made from almond flour, or yogurt made from coconut.
What *Not* to Eat on the Paleo Diet
The foods eschewed on the paleo diet are things that our ancestors allegedly did not eat (although we don’t actually have solid proof of what Paleolithic humans did or did not dine on).
Here’s what gets the ax on the paleo diet:
Grains: The paleo diet strictly excludes grains of all kinds: rice, flour, bread, cereal, oats, popcorn, etc. Grains can technically be “gathered,” but they weren’t eaten to the extent by our ancestors to the extent they are now until the invention of milling, especially the more efficient, modern forms of milling. Supporters of the paleo diet believe this processing strips away all nutrients of the grain and contributes to the development of diseases.
Dairy: Milk products are also considered a “modern” invention. Europeans began drinking milk about 7,500 years ago, as estimated in a study published in PLoS Computational Biology. (The Paleolithic era was 2.6 million years ago.) Those who swear by the paleo diet point to high prevalence of lactose intolerance—65 percent of the global population, according to the U.S. National Library of Medicine—as an indication that cow’s milk is not intended for human consumption.
Legumes: Foods like peanuts, black beans, lentils, hummus, and tofu are all off limits on the paleo diet. They may come from the earth, but paleo eaters say legumes contain something called phytic acid, which may interfere with the absorption of certain nutrients (like iron and zinc).
Sugar: This one doesn’t take a lot of explaining. Cavemen weren’t eating Twix and drinking Mountain Dew. The American Heart Association (AHA) says sugar contributes “zero nutrients but many added calories,” which can affect weight and heart health. Some people on the paleo diet avoid all sweeteners, while others may allow, in moderation, so-called “natural” forms like raw honey or coconut nectar. (Check out these benefits to eating less sugar.)
Heavily processed foods: Like sugar, this one is intuitive. Heavy food processing is a modern invention, and paleo eaters argue it strips food of its natural nutrients and provides humans with an excess of harmful ingredients, like sugar, sodium, and refined grains.
So, What’s the Big Deal with the Paleo Diet?
Going paleo has a few obvious perks. First, cutting sugar and heavily processed foods can eliminate problematic aspects of the Standard American Diet. Most health organizations promote a similar message; however, note that the AHA does not advocate removing all sugar entirely—just limiting to to 100 to 150 of your daily calories.
Another benefit of the paleo diet is its emphasis on fruits and vegetables. Consider that trendy side dishes like cauliflower rice and zoodles, for example, were popularized by the paleo crew, and you’ll see how veggies tend to play a big role on a paleo diet. That’s definitely not a bad thing.
And choosing lean proteins in recommended portion sizes, eating nuts and seeds, and consuming ample veggies are all habits endorsed by the U.S. Department of Agriculture, the Academy of Nutrition and Dietetics, the AHA, and more.
OK, So What’s the Catch with the Paleo Diet?
Basing an entire food system off Paleolithic ancestors is shaky reasoning. “Paleolithic hunters weren’t the lean, healthy people we imagine,” says Morton Tavel, MD, clinical professor emeritus of medicine at Indiana University School of Medicine.
“Excavations of hunter-gatherers have revealed that they had all kinds of health problems,” says Dr. Tavel, “including the fatty build-up in the arteries that still plagues their descendants.”
Additionally, researchers aren’t even entirely sure of what “cavemen” actually ate. In fact, some studies have found evidence that Paleolithic humans survived mostly on plant foods (and less on hunted meat) than we thought, according to Dr. Tavel.
Accuracy aside, the paleo diet might do more harm than good when it comes to health—the very thing it aims to cure. In a 2014 study of over 16,000 adults, those who consumed more animal protein had higher risk of type 2 diabetes than those who consumed mostly plant protein (such as legumes).
Cutting grains is also a cause for concern among many nutrition experts. Whole grains provide fiber and B vitamins, and their fiber content is great for regular digestive health. A study in Nutritional Journal found that people who ate three servings of whole grains daily lowered their risk of colorectal cancer by 17 percent.
As for preventing diseases, the American Diabetes Association lists beans, whole grains, milk, and yogurt as “superfoods” due to their ability to provide important nutrients that sustain good health. The American Institute for Cancer Research also cites legumes and whole grains as powerful weapons against cancer.
Should You Try the Paleo Diet?
While there are aspects to the paleo diet that might make you more mindful of the foods you’re choosing, it may not be wise to commit 100 percent. “Eating a natural diet” sounds promising, but the paleo diet makes too many promises based on unclear science. As Dr. Tavel says, “Historical accuracy isn’t the same as nutrition.”
Ultimately, any positive results from following the paleo diet are likely to be temporary, as this kind of restrictive diet is hard to stick to. Instead, a balanced diet comprised of lean protein, whole grains, legumes, fruits, and vegetables is probably a better way to go. Most health organizations recommend the Mediterranean diet as a more sustainable (and healthy) way of eating.