Everything You Need to Know About the Paleo Diet

The new, old diet

The paleo diet (also nicknamed the caveman diet, primal diet, Stone Age diet, and hunter-gatherer diet) is hugely popular these days, and goes by one simple question: What would a caveman eat? Here, we explain what the paleo diet involves, its pros and cons, and, ultimately, what a modern person needs to know to decide whether or not to take the paleo diet plunge.

2 of 14 Getty Images

The paleo premise

The paleo diet runs on the same foods our hunter-gather ancestors supposedly ate: fruits, vegetables, meats, seafood, and nuts. "By following these nutritional guidelines, we put our diet more in line with the evolutionary pressures that shaped our current genetics, which in turn positively influences health and well being," says Loren Cordain, PhD, professor of health and exercise science at Colorado State University and author of The Paleo Diet. He says the diet lessens the body's glycemic load, has a healthy ratio of saturated-to-unsaturated fatty acids, increases vitamin and nutrient consumption, and contains an optimal balance of protein, fat, and carbohydrates.

3 of 14 Getty Images

Experts don't agree on its benefits

In fact, the health benefits of the paleo diet are unproven. "Our ancestors ate this way and didn't have many of the chronic diseases we do, but that doesn't mean the food they ate is the reason why; drawing that conclusion would be like saying we live three times longer than our Paleolithic ancestors because we eat fast food," says Christopher Ochner, MD, research associate at the New York Obesity Nutrition Research Center at St. Luke's and Roosevelt Hospitals. Still, a handful of small studies have tried to determine if a paleo diet is a healthier diet. One small study published in the journal Diabetologia found that the diet improved blood sugar over 12 weeks compared to a Mediterranean one that allowed grains, low-fat dairy, and oils, but it's hard to say whether researchers would come to the same results in a larger study.

4 of 14 Getty Images

What's on the menu?

Fresh fruits, fresh vegetables, fresh meat—the paleo diet is all about eating foods straight from the Earth just as our ancestors did. Those ancestors didn't have livestock or crops to call their own, so Cordain advises to go with grass-fed and organic varieties whenever possible to limit exposure to pesticides, antibiotics, and other chemicals that didn't exist back then. Research from Emory University suggests that Paleolithic people obtained about 35% of their calories from fats, 35% from carbohydrates, and 30% from protein.

5 of 14 Getty Images

Paleo comes with community

One of the biggest pluses of the paleo diet isn't about nutrition at all—it's about the support paleo eaters give each other. Online community forums, Facebook pages, and even Meetup groups are filled with people living the ancient lifestyle in modern times. You won't find that with many other diets.

6 of 14 Getty Images

Going paleo means giving up modern foods

Anything that comes in a box, jar, or bag should be avoided on the paleo diet—as should anything that just wasn't consumed back then. That means no grains, dairy, added salt, or legumes (including peanuts, beans, lentils, and soybeans), according to Robb Wolf, a former research biochemist, paleo expert, and author of The Paleo Solution. While potatoes are generally outlawed on the diet, Wolff says they are okay to eat sparingly as long as you earn them through exercise (more on that next). Alcohol and honey are also generally considered paleo no-nos, but red wine tends to be the closest option there is to a paleo drink, and honey is far preferred to table sugar or artificial sweeteners.

7 of 14 Getty Images

Paleo is a lifestyle

"The paleo diet is by no means a temporary diet," says Cordain. It's meant to be a lifestyle, just as it was thousands of years ago. You don't just stop it if and when you start feeling better or reach your goal weight—you stick it out for the long haul.

8 of 14 Getty Images

Paleo isn't just about food

Exercise is a vital part of the live-by-your-genetic-code equation. Surviving in the Stone Age meant a constant on-the-go lifestyle that probably required 4,000-plus calories a day, according to David L. Katz, MD, director of the Yale University Prevention Research Center. Even most people who hit the gym regularly won't need to eat that many calories, but the principle of using food as fuel to exercise still stands.

9 of 14 Getty Images

Cutting out processed foods improves health

While the diet as a whole hasn't been well studied, the benefits of cutting packaged foods from your diet could be huge. According to the Harvard School of Public Health, three quarters of the average American's sodium intake (which is almost double what it should be!) comes from commercially prepared foods. And, one Public Health Nutrition study found that people who cook at least five times a week are 47% more likely to be alive 10 years later compared to those who rely more on processed foods.

10 of 14 Getty Images

It's impossible to completely mimic our ancestors

Our ancestors didn't chase cows and chickens around in the wild. They hunted game, antelopes, buffalo, and probably some animals we've never heard of that are long extinct. Their meat was generally quite lean, and provided more healthy omega 3s than meats from modern day animals, even the grass-fed ones, according to Dr. Katz. Many of the plants that thrived back then are also extinct today, making it impossible to truly follow their meal plan, he says.

11 of 14 Getty Images

You can eat too much protein

Experts estimate that our ancestors consumed a one-to-one ratio of calories from meats to produce. Since you have to eat a lot of salad to consume the same amount of calories in a steak, the paleo diet should ideally include mostly fruits and vegetables, Katz says. However, many people don't realize that and eat too much meat. Consuming excess protein and not enough carbs can cause kidney damage and also increase your risk of osteoporosis, Dr. Ochner says. Plus, since most of today's meats are higher in saturated fat than those of yesteryear, it can increase the risk of heart disease, Dr. Katz says.

12 of 14 Getty Images

Many of paleo's banned foods are good for you

"Every fad diet thinks it has discovered the root of all evil," says Dr. Ochner. But nutrients in legumes, whole grains, and dairy—all of which are forbidden on the paleo diet—can help to lower the risk of osteoporosis and cardiovascular disease, reduce blood pressure, and promote a healthy weight, he says. Cutting dairy, the primary source of calcium and vitamin D in modern diets, is especially worrisome for women who want to avoid osteoporosis.

13 of 14 Getty Images

The paleo diet is difficult

Paleo eating requires a lot of planning, prep time, and mental resolve. For instance, eating out on the diet isn't as simple as ordering chicken and a salad. Think: In what oil was the chicken cooked? Did any of the salad toppings come processed, canned, or packaged? "As with every elimination diet, it's just not doable long term," Dr. Ochner says. While weight loss is far from the sole purpose of eating paleo, going on and off of the diet can lead to big weight swings. Any yo-yo diet starts in weight loss from both muscle and fat, and usually ends with weight gain of all fat, which contributes to a slower metabolism and increased insulin resistance.

14 of 14 Getty Images

Paleo can be expensive

Following the paleo diet can be pricey. Inexpensive and healthy non-meat protein sources like soy and beans are off-limits, and a recent BMJ Open study shows that healthy meats like lean ground beef and boneless, skinless chicken breasts cost an average of 29 cents more per serving compared to less-healthy ones, such as high-fat ground beef and chicken drumsticks. Even switching from peanut butter to paleo-approved almond butter will cost you—it goes for up to $13 a jar.