A number of eating fads have gained popularity in recent years, but one diet that has stuck it out through thick and thin is that of the Paleo regime. Whether consumers agree or disagree with this caveman style of eating, it’s one diet that most people have at least heard of, although not one all sufficiently understand.

Many associate the Paleo diet with Crossfit — the strength and conditioning program founded by former gymnast Greg Glassman in the 1970’s — however, Crossfitters and non-Crossfitters alike enlist this program to achieve their desired physical results, and they have significant support backing their logic.

Health experts harbor different sentiments on the popular dietary fad that is Paleo, with some citing the benefits of eating like the cavemen while others arguing for its unhealthiness, but arguably one of the biggest pros of the diet is the extensive information supporting the lifestyle choice, along with explanations how to go through with it.

Here’s the who, what, when, where, why, and how of the Paleo diet so you can better understand the logic behind this eating phenomenon. Paleo certainly doesn’t have to be an all-or-nothing thing, unless you have a Crossfit coach breathing down your neck of course, but advocates of the plan swear that the desired results can only be achieved if one commits to the approach wholeheartedly. See what you think.

1. The “What”

Going a little out of order, we begin with the “what” of the Paleo diet — what Paleo is, where it gets its name, and what the diet is all about. Diving in headfirst, according to UltimatePaleoGuide.com, the Paleo diet is the way of eating that focuses on eating food the way humans ate before the last 10,000 years, hence the name “Paleo,” which means “older or ancient.”

The Paleo diet encourages consumers to eat only the way nature intended, or the way our ancestors ate during the Paleolithic period before grains and other processed foods were introduced into diets, because there is a belief that our bodies “evolved” based on what our ancestors ate prior to the advent of agriculture, and archaeological evidence shows that hunter-gatherer peoples tended to be healthier than agriculturalists. Their bones do not show evidence of the same level of diseases found in the remains of agricultural peoples.

Thus, because our ancestors survived off real, whole foods like vegetables, lean meats, nuts and seeds, the Paleo approach encourages the mirroring of that hunter/gatherer lifestyle.

Paleo advocates argue that our current diet is only the way humans have been eating for the past 10,000 years, and it is that Standard American Diet (or, SAD), that currently revolves around large amounts of refined sugar, carbohydrates, and other processed foods that is to blame for the unhealthy food regimes that many people now sustain and suffer poor health from.

The Paleo regime is a diet that some enlist for physical performance and others for weight loss purposes. Whatever the case, the theory behind the Paleo diet is that you can eat like a caveman and shed pounds without counting calories.

According to Web MD, Loren Cordain, PhD, author of the book The Paleo Diet, claims that by eating like our prehistoric ancestors, we’ll be leaner and less likely to get diabetes, heart disease, cancer, and other health problems. This high-protein, high-fiber eating plan is also called the Caveman Diet or the Stone Age diet.

2. The “Who” and the “Where”

Next up, we’ll talk about the “who” behind the Paleo diet, because many onlookers often associate the Paleo lifestyle with their Crossfitting friends, and there’s a reason why. LiveStrong.com says that most Crossfit coaches encourage their athletes to follow Paleo regimens because the eating approach mirrors the exercise program’s own dietary guidelines.

Crossfitters believe that the Paleo diet leads to the best athletic performance, because like the Zone diet, which Crossfit originally pushed, Paleo advocates a specific ratio of carbs, protein, and fats, and it is relatively easy to follow. Crossfitters believe that Paleo enhances performance because, according toFitbie, muscle growth is stimulated by branch chain amino acids, and lean proteins are a good source of them while grains are a poor one. On the Paleo diet, consumers eliminate grains and eat more meat, so they get more muscle-building protein.

The Paleo diet also adds to the tribal, “culty” mentality of CrossFit. Crossfitters want to feel part of something, almost counter-cultural with both their eating and exercise habits, and the atypical Paleo diet supports those intentions and sets them apart from the crowd.

But, of course, non-Crossfitters take part in the eating regimen too — and many stand by the belief that Paleo not only stimulates muscle building, it also helps participants shed pounds.

Non-crossfitters who choose to eat Paleo are usually interested in backing away from processed foods that contain preservatives, salt, and sugars. Eating Paleo doesn’t guarantee that consumers are making better food choices, but it does make it harder to indulge in the processed food that many humans love to love and health experts love to hate.

3. The “How”

Up next is the tricky part: actually following the Paleo dietary plan. Arguably, the Paleo diet is more defined by what you cannot eat, rather than what you can eat. As aforementioned, Paleo dieters can’t eat any processed foods meaning no wheat, dairy, potatoes, salt, and refined vegetable oils like canola oil.

They can eat lean meats and fish, fruits, vegetables, eggs, nuts, seeds, and natural oils like coconut, olive, and avocado oil. Navigating the Paleo rules and regulations might sound complicated, but theUltimatePaleoGuide.com says a good rule of thumb for Paleo is that if a food comes in some sort of cute packaging, it’s probably not Paleo. Don’t forget that Paleo entails no wheat and dairy. Many consumers forget those foods are processed. Case in point: go for the meat and veggies rather than the bread and dairy.

As for Crossfitters following Paleo, the program encourages participants to to follow a plan where calories should be broken up into protein 30 percent, carbohydrates 40 percent, and fat 30 percent. Paleo programs also support trying the diet for 30 days and then seeing how the body reacts. Branded “Whole 30,” dieters are told to follow the diet religiously, and the trial run leaves room for cheating. When consumers are just starting out, they get three cheat meals a week, but those are eventually taken away.

4. The “Why”

Paleo advocates get a lot of grief because some experts say that the diet encourages excess consumption of fat. Supporters of the diet disagree, especially Crossfitters. They say that our bodies’ preferred source of energy is fat because fat is a much slower burning fuel, and is thus more efficient for our body to use.

According to UltimatePaleoGuide.com, people in the pro-Paleo camp argue that fat gets a bad rap because most humans typically consume an excess of carbohydrates, so our bodies burn the carbohydrates rather than fat, and we’re left with excess fat that gets stored for later use. However, by reducing the amount of cheap carbohydrates in consumers’ systems, the Paleo diet allows bodies to start the process of burning fat.

As for those carbs, the Paleo diet does permit some, but advocates argue that dieters should not consume simple carbohydrates like white bread and pasta because simple carbs break into sugar quicker, and trigger a insulin response that keeps consumers’ insulin levels elevated. When insulin levels are up, the body is prevented from burning fat through a process called lipolysis. On the other hand, complex carbs — the kind that Paleo supports — take longer to break down and thus don’t spike insulin levels as quickly as simple carbs do.

5. The “When”

So, when is following Paleo a good idea? Some say all the time, while others say never. Now that you have a basic understanding of the Paleo diet, you can decide for yourself whether you support the regime or not, but health experts offer differing views. Those in the pro-Paleo camp usually stick with the aforementioned logic and arguments behind the diet, while those against it make a number of different claims. One such claim, highlighted by Scientific American, argues that we as humans are not biologically identical to our Paleolithic predecessors, nor do we have access to the foods they ate, so following their dietary plan is illogical.

Evolutionary biologist Marlene Zuk argues in her book, Paleofantasy, that the Paleo diet fails to take into account the fact that through our evolution, we have inherited many adaptations from our Paleo predecessors, and we are not identical to stone-age humans, so not taking advantage of our new modern methods of eating does not make sense. If humans and other organisms could only thrive in circumstances similar to the ones their predecessors lived in, life would not have lasted very long.

As for the nutrition side of things, some registered dietitians believe that eliminating several food groups like dairy and grains is not nutritionally sound because these groups provide essential nutrients, such as calcium, vitamin D, magnesium and phosphorus in dairy and B vitamins, fiber, and antioxidants in grains.

According to The Huffington Post, Lisa Sassoon, a registered dietitian and assistant clinical professor of nutrition at NYU, argues in regards to the diet, “There’s no real research behind it either. And it eliminates things that do have research behind them: grains, beans, and low-fat dairy.” A dietician who shares her assertions, Joy Dubost, says that nutrients in legumes, whole grains, and dairy help to lower one’s risk of osteoporosis and cardiovascular disease, reduce blood pressure, and maintain a healthy weight.

Both experts also argue that following a Paleo diet makes it too easy to choose cuts of meat that are high in the bad LDL cholesterol and saturated fat.

Consumers eliminate dairy on the diet, meaning they no longer getting that fat via dairy, but some of the foods that are forbidden for Paleo eaters, like whole grain oats, beans, and other grain and legume sources of fiber have been found to help moderate cholesterol levels, so without them, consumers are at risk. Sassoon and Dubost advocate paying close attention to portion size, rather than restricting certain food groups all together.

There you have it: the Paleo diet and the popular arguments from pro- and anti- camps. Whether or not you think you’re ready to jump on the pro-Paleo bandwagon, at least you now understand the logic behind the diet, and are not confused when you’re Crossfitting coworkers are eating meat and vegetables for breakfast, lunch, and dinner.