The Primal Blueprint, created by fitness and lifestyle guru Mark Sisson, helped to kick off the enormous paleo movement two decades ago. With it came stories of people losing weight, shedding disease, and feeling better about themselves, but there also came accusations of bad science and outright deception. What’s the truth?

We’ve waded through the science to help you better understand what the Primal Blueprint is, what it promises to do (and what it doesn’t claim), plus which of those claims hold up and which don’t. Ready? Grab your caveman gear and let’s go!

The Model for Paleo

Primal Blueprint, like many wildly popular phenomenon, originated with a story. Before the creation of the blog in 2003, Mark Sisson was an athlete. He competed in the 1980 US Olympics, going on to become a well-respected triathlete, finishing 4th in the Hawaiian Ironman and (earlier in his career) 5th in the National Marathon Championships.

Despite being in far better shape than most people, however, Mark often found himself sick. He reports experiencing issues such as tendinitis, gastritis, arthritis, sinusitis, and others, and felt frustrated that, if he wanted to stay lean and keep the weight off, it was looking like he’d have to spend hours and hours at the gym.

There Must Be a Better Way

As Sisson began to research, he began to believe there was a different, better way. As he began to study the eating habits and lifestyle behaviors of what he calls our “primal ancestors,” Sisson began to feel a connection between their behaviors and a potentially better quality of life.

Mark claims that while the world has changed significantly in the last ten centuries, the human genome hasn’t, and while our ancestors moved constantly and enjoyed “natural” foods, we sit for huge amounts of time during the day as well as eat extremely processed foods filled with artificial ingredients like fats and sugars.

Not What Your Ancestors Ate

Mark claims that that paleo way of eating addresses these problems and he created the Primal Blueprint to help people easily understand how to eat and find community. His first book, also called the Primal Blueprint, sold half a million copies and had made the Wall Street Journal and Amazon’s best selling lists.

In it, Sisson teaches followers that, no matter how large the quantity of sugar and carbs you consume, your body will only utilize what it immediately needs for energy. The rest is converted into fat, which means that a diet high in sugar and carbs will ultimately lead to weight gain.

Chronic weight gain, Sisson explains, over years of poor eating choices, can lead to a variety of health problems, some of which might even threaten your life.

Is Paleo Based on Science?

Ultimately, the primal health diet that Sisson claimed worked so well for him and the one he espouses in his Primal Blueprint is the paleo diet. Many people confuse paleo with the Atkins diet, but a paleo diet (also called a primal diet) isn’t the same thing. Here, in fact, is what paleo isn’t:

Paleo Diet

Image via paleocorner

It’s Not a Diet

One of the reasons people often see such huge results on a paleo diet is that it’s not a diet. Here’s what we mean: a diet by traditional standards is very restrictive. Think of the major diets that have become popular over the years–things like Weight Watchers or Slim Fast. These diets are extremely restrictive and tend to focus on things that people can’t eat or limit what people can eat altogether.

What we know about human behavior is that people are more likely to stick to something when they don’t feel they’re being restricted. When people can say “I don’t eat this” instead of “I can’t eat this,” they are much more likely to stick to their choices and resolutions.

Because paleo focuses on sustainable lifestyle changes, advocates can sustain it for the long-term, reshaping their eating habits for the better instead of simply gritting their teeth and eating flavorless food for a period.

In fact, many of people’s favorite foods–like bacon and chocolate–are on the menu in the Primal Blueprint diet!

It’s Not an Excuse to Eat Bacon

Speaking of bacon, it’s common for people to confuse the Primal Blueprint or the paleo lifestyle in general with a giant meat fest, and while paleo followers certainly don’t miss an opportunity to wrap a vegetable in bacon, true paleo advocates understand that a diet focused on meat isn’t the answer, either.

In fact, the truest forms of paleo simply eschew modern forms of food–like gluten and corn syrup–in exchange for foods they believe ancestors ate, such as wild game, free-range eggs, organic, locally grown vegetables, and so forth.

Cavemen (what paleo devotees call themselves) believe that once you’re off processed foods laden with preservatives, sugars, and man-made fats, your taste buds can appreciate the abundant and delightful variety of flavors and textures found in nature. Those who claim it’s all about the meat are, in fact, perverting paleo in its truest sense.

Instead of what paleo isn’t, let’s talk now about what paleo–and the Primal Blueprint–are.

What Is Paleo All About?

Paleo is a lifestyle that seeks to live the way our ancestors did centuries ago. This includes eschewing processed foods, like Twinkies or chips, in exchange for whole foods that haven’t been processed or tampered with. Pasta, cereals, dairy products, and bread are out, and leafy green vegetables, nuts, and grass-fed meats are in!

The Primal Blueprint, we should note, isn’t the same as paleo. Most people use primal and paleo interchangeably, but there are some differences, namely in how each views legumes, dairy, coffee, and saturated fats.

The Difference Between Primal and Paleo

Paleo, for example, view legumes and dairy as problematic for all people thanks to some nasty enzymes (if you’re doing the Whole30, for example, you’ll need to avoid both). Primal is a little more open, focusing on avoiding those things if they are a problem for you. Sisson doesn’t believe, however, they’re a problem for everyone.

The other big difference between paleo and primal isn’t such a big difference anymore: saturated fat. The paleo camp long believed saturated fats (like butter and coconut oil) were huge problems, while the primal movement embraced the two.

Now, however, both camps are equal opportunists when it comes to high quality, grass-fed butter, and coconut oil!

The Truth Comes Out

As popular as the paleo lifestyle and the Primal Blueprint has been, they’ve also had more than their fair share of critics. Let’s take a closer look at some of the questions raised about this lifestyle and determine whether or not they’re worth heeding:

Humans HAVE Changed a Lot

One of the cornerstones of paleo logic is that, as we mentioned earlier, the human genome has not changed significantly. In fact, it has changed significantly. Paleo detractors point to how our bodies have developed a tolerance for lactose the protein found in milk in response to consuming dairy. This adaptation has only occurred in the last 7,000 years.

Other adaptations include the gene for blue eyes, a gene that makes individuals who live in mosquito-infested climates resistant to malaria, and even a gut bacteria that help us fight local and common pathogens. There’s no way of knowing for sure what kinds of bacteria people had in their guts ten centuries ago, but it’s probably safe to say they had different bacteria than we do.

What this means for us is that, while avoiding processed foods makes sense for just about everyone, eating like our ancestors did doesn’t. Even the foods that we, today, enjoy in their most natural state–like broccoli or tomatoes–have evolved so dramatically over the centuries that they no longer look, taste, or behave like the original thing.

In addition to finding flaws in the logic behind the paleo diet, detractors also point to other studies (the China Study is a popular one and advocates for a vegan diet) that find contrary results.

What’s the Bottom Line?

The bottom line for us–and, we think, for most people who take an honest look at the science–is that some people will do better on one type of diet or another, but everyone benefits from eating whole food, less processed food, and more vegetables.

Whether it’s better primal endurance, the eradication of diseases like diabetes or arthritis, or overall better health and wellbeing, it’s worth taking the time to discover what fuels your body and makes you healthier. Here’s to great health, whether it’s primal, paleo, or otherwise!

Feature image via google help.primalblueprint.com