The Paleo Diet: How It Works, What to Eat, and the Risks

Obesity, heart disease, and diabetes: These are just a few of the health conditions that proponents of the Paleolithic diet, or caveman diet, blame on our sedentary lifestyles and modern way of eating, which is loaded with sugar, fat, and processed foods. Their proposed solution? Cut modern foods from our diet and return to the way our early hunter-gatherer ancestors ate.

To get an idea of what that means, we turned to the experts, including Loren Cordain, PhD, a professor emeritus at Colorado State University in Fort Collins and the author of The Paleo Diet; Erin Holley, RD, of The Ohio State University Wexner Medical Center in Columbus; and Lona Sandon, PhD, RD, an associate professor of clinical nutrition at the University of Texas Southwestern Medical Center in Dallas.

For starters, to be and stay healthy on the paleo diet, Dr. Cordain says that you’ll need to exercise regularly while following a strict diet made up of only foods that can be hunted and gathered.

In its purest form, the paleo diet allows you to eat just those foods that humans ate when they first roamed the planet about 2.5 million years ago.

The diet can improve your health by eliminating high-fat and processed foods that have little nutritional value and too many calories. This plan emphasizes loading up on fruits and vegetables that are bursting with healthy vitamins, minerals, and fiber, which fills you up faster so you eat less, helping curb weight gain, according to research.

You’ll lose weight because anytime you restrict entire food groups, your calorie intake tends to be lower, Dr. Sandon says. And according to the National Heart, Lung, and Blood Institute, whenever you burn more calories than you consume, you'll lose weight. The focus on lean protein, fruits, and vegetables over calorie- and sodium-rich processed foods can also contribute to weight loss, according to research on other diet plans that incorporate these tenets of healthy eating. But Sandon points out that the paleo diet wasn’t created to be a weight loss diet.

Although nuts and seeds are allowed on this diet, they can be high in calories, and people who want to lose weight will have to limit their nut consumption.

So what does the science say about the paleo diet? Some research suggests that the health claims hold water. A review that analyzed four randomized, controlled trials totaling 159 participants found that the paleo diet led to more short-term improvements in some risk factors for chronic disease (including waist circumference and fasting blood sugar) compared with diets used as controls.

Another article reviewed clinical trials that explored the effect of paleo on health markers like weight, inflammation, and insulin health. Some of the studies found similar evidence that the paleo diet may be linked to weight loss, lower blood pressure, and improved blood lipid levels, but the authors concluded that because of the small sample sizes, short durations, and similar frameworks of most existing studies on this diet, further research is needed to prove whether it lives up to the bold health claims made by some of its proponents.

In fact, many scientists have expressed concern that we do not yet have enough evidence to make any strong claims about the paleo diet’s health benefits, especially its long-term effects. In response to the first review, authors Tanis R. Fenton and Carol J. Fenton, of the University of Calgary Cumming School of Medicine in Alberta, expressed their disappointment in a letter to the editor.

Among their arguments: Some of the results were not statistically significant, nor did they show “any important clinical effects.” They concluded that they did not believe that the results of the review showed any evidence in favor of the paleo diet, and they called for more care in reaching health recommendations for the general public.

On the paleo diet, you’ll find fewer processed foods, but you’ll also need to cut out all grains, legumes, and most dairy. Here’s a closer look at the eating plan.

What to Eat

Although the paleo diet isn’t proven to work, if you want to give this eating plan a try, you’ll need to prioritize fueling up on lots of natural foods and natural fats, including these options:

• Lean cuts of beef, pork, and poultry, preferably grass-fed, organic, or free-range selections
• Game animals, such as quail, venison, and bison
• Eggs, but no more than six a week and preferably free-range
• Fish, including shellfish
• Fruit, such as strawberries, cantaloupe, mango, and figs
• Nonstarchy vegetables, such as asparagus, onions, and peppers
• Nuts and seeds, including almonds, cashews, walnuts, and pumpkin seeds
• Olive oil, flaxseed oil, and walnut oil, in moderation

What to Avoid

Similarly, any foods that were not easily available to Paleolithic humans are off-limits in this diet, Holley explains. That means processed foods — many of which contain added butter, margarine, and sugar — should not be a part of the paleo diet. The same goes for dairy, which may not have been accessible to Paleolithic humans, and legumes, which many proponents of the diet believe are not easily digestible by the body.

Keep in mind that some versions of the paleo diet are less strict than others and allow some dairy products or legumes, like peanuts, Holley says.

Foods to avoid:

• All dairy products, including milk, cheese, yogurt, and butter
• Cereal grains, such as wheat, rye, rice, and barley
• Legumes, like beans, peanuts, and peas
• Starchy vegetables, such as potatoes (and some even say sweet potatoes)
• Sweets, including all forms of candy as well as honey and sugar
• Artificial sweeteners
• Sugary soft drinks and fruit juices
• Processed and cured meats, such as bacon, deli meats, and hot dogs
• Highly processed foods

The paleo diet has become one of the most popular eating approaches out there, so you won’t have trouble finding a bounty of paleo-friendly recipes online and on bookshelves. But if you’re a beginner, consider this one-day sample menu of the paleo diet to get you started.

Breakfast Onion and spinach omelet with liver pâté

Lunch Tuna wrapped in lettuce with almonds

Snack Hard-boiled eggs

Dinner Beef bourguignon

Dessert Ice cream made from coconut milk

While the paleo diet is certainly not a cure-all, it does come with some potential benefits. But that doesn’t mean it’s for everyone — there are also some risks you should be aware of before diving in.

Potential Pros of Following the Paleo Diet: It’s Nutritious and Easy to Follow, and It Involves Exercise

There are a handful of benefits you'll potentially reap from following the paleo diet.

First, by eating fruits and vegetables, you’ll get many of the essential vitamins and minerals you need.

Also, the diet is simple. You eat the foods that are acceptable and avoid those that are not — there’s no meal plan or diet cycle to stick to.

“I think there are a lot of positives about it,” Holley says. “It cuts out a lot of processed foods just naturally, like processed grains or added sugar through soft drinks or juice.” And because the diet promotes eating anti-inflammatory foods — like fruits, vegetables, and unsaturated fats in nuts and certain oils — your health could benefit, Holley explains. As research shows, cutting out processed foods and sugar will also lower your risk of diseases, too, like type 2 diabetes and certain cancers, she says.

Furthermore, the diet emphasizes exercise. Exercise is an important part of a healthy lifestyle and can help you lose or maintain your weight, says the Centers for Disease Control and Prevention (CDC).

Possible Cons of Following the Paleo Diet: Cost, Difficulty, and Limited Evidence

But a hunter-gatherer diet can be difficult to maintain, especially long term. Because most foods are eaten plain, following the eating approach can get boring after a short time.

It can also be expensive because foods that are organically grown and grass-fed beef and other meats typically cost more, notes Consumer Reports. For example, one model based on data from the U.S. Department of Agriculture found that a 9 percent increase in income would be necessary to follow the paleo diet while meeting all daily recommended micronutrient intakes (except for calcium), according to research. More recent data has affirmed that the paleo diet is more expensive than other eating plans, such as the Mediterranean diet, and it has a higher carbon footprint — meaning it’s also not as environmentally responsible.

And again, there’s no concrete scientific proof that the paleo diet wards off disease, Sandon says. Any evidence of its benefits is anecdotal. Although some studies seem to support the benefits of the paleo diet, many scientists still believe we don’t yet have enough evidence to know whether the eating approach is totally healthy and without risk. “Nobody knows the long-term effects of this diet because no one has researched it to any degree,” Sandon says, adding that it’s not really a new concept but one that’s been recycled through the years.

For instance, the fat allowance of the diet may be problematic. “My biggest hang-up with the paleo diet is all the saturated fats it promotes with all the meats,” explains Holley, noting that you could look for locally sourced meat, for which you are aware of the origin and method of raising, as a healthier option. Saturated fat from meat has been linked with an increased risk of early death, research has found.

Research highlights the potential calcium deficiency as a significant issue with the paleo diet. One study found that calcium intake levels among followers of the paleo diet were as low as 50 percent of the recommended daily value. Per the National Institutes of Health Office of Dietary Supplements, calcium deficiency can cause symptoms including numbness and tingling in the fingers, muscle cramps, convulsions (or muscle spasms), lethargy (or lack of energy), low appetite, and abnormal heart rhythms. Chronic calcium deficiency may lead to skeletal disorders such as osteoporosis, increased risk of bone fractures, and rickets. A registered dietitian can help you follow this plan safely and avoid deficiency in nutrients like calcium.

While there’s no perfect diabetes diet, some research suggests that the paleo diet’s focus on whole foods may help people with type 2 diabetes manage their blood sugar, lower their blood pressure, and lose weight.

Critics argue that the unlimited amount of red meat that the paleo diet allows may have an adverse effect on heart health in people with diabetes, since research links eating red meat in excess to poor heart health. If you have diabetes and don’t moderate your intake of red meat, this could be a big problem, as people with diabetes are twice as likely to die of heart disease as people who do not have diabetes, says the CDC.

The takeaway: Essentially, there aren’t enough encouraging study results for experts to make a formal recommendation for people with diabetes to try the paleo diet. If you want to try the plan with the aim of managing your blood sugar, be sure to clear it with your healthcare provider first.

As with type 2 diabetes, the paleo diet may or may not be good for your heart. It comes down to how you follow the eating approach.

If you were to eat an unlimited amount of red meat (which the paleo diet technically allows), you would most likely see your heart health suffer. While experts applaud the omission of packaged and processed foods like cakes, cookies, chips, and candy — which are well known to be bad for your ticker — they’re not crazy about the fact that paleo doesn’t allow you to eat whole grains, legumes, and most dairy. Whole grains in particular have been linked with better cholesterol levels, as well as a reduced risk of stroke, obesity, and type 2 diabetes, according to the American Heart Association. These are all comorbidities of heart disease, per the National Institute of Diabetes and Digestive and Kidney Diseases.

The gist? Talk to your doctor before trying the paleo diet for heart disease. They will be able to tell you if it’s a good fit and, if so, how you should approach the plan for optimal health.

Although research on the paleo diet’s possible role in helping manage autoimmune diseases is limited at best, researchers’ and paleo proponents’ interest in this prospect isn’t waning. There’s even a niche paleo diet for this very purpose called the autoimmune paleo diet.

While proponents of the paleo diet say they’ve anecdotally seen the diet help control inflammatory bowel disease, psoriasis, eczema, multiple sclerosis, celiac disease, and Hashimoto’s thyroiditis, research on these effects is lacking.

Definitely don’t expect paleo to be a panacea for any autoimmune disease you may be managing, and be sure to consult your doctor before diving in.

You could lose weight following a Paleolithic diet — and quickly, too, depending on how strictly you adhere to eating the foods from the allowed list and how much physical exercise you add to your daily routine.

In the long term, you have to be sure that you’re getting calcium and other nutrients you’re missing by not having dairy products and certain grains. Some paleo-approved foods, such as salmon and spinach, contain calcium, so you have to be sure you’re including them in your diet. It would be a good idea to check with a registered dietitian, too, to make sure you’re meeting your calcium and other nutrient needs.

On the whole, the paleo diet is not a bad choice, Holley says. If someone follows the diet by cutting out processed food, processed meats, and sugar-sweetened beverages and swaps them for more fruits, vegetables, and healthy fats, they’re likely to see some health benefits.

“One thing to consider is how extreme you want to take it,” says Holley, noting that some versions of the diet are more restrictive than others, limiting foods like dairy or peanut butter. It could be overwhelming to cut out a bunch of food groups all at once. Holley suggests trying small incremental changes instead.

“I’m always of the mindset that if we completely change everything at once, it’s less likely to stick. If we make gradual changes, we’re more likely to hang on to these things,” Holley says.

Overall, the diet is not for everyone, but it could be helpful to some, Holley says. “It’s important for each person to carefully understand the diet before they jump in.”

Before making any changes to your diet or exercise plan, be sure to speak with your physician to make sure that the changes you would like to make align with your personal health needs.

Favorite Resources for Info About the Paleo Diet

The Paleo Diet

Cordain is the founder of the paleo diet movement and a professor emeritus at Colorado State University in Fort Collins. His website has all the info you need to get started on your paleo journey, from what to eat to the latest research on the caveman diet.

Diet Review: Paleo Diet for Weight Loss

Harvard University's T.H. Chan School of Public Health delivers an unbiased look at the research on paleo and the benefits and risks of putting the diet into practice in real life. If you’re looking to learn the scientific truth about this eating plan, you’ll want to check out this resource.

Favorite Paleo Diet Blogs

PaleOMG

PaleOMG is run by Juli Bauer, who has also published several cookbooks. Her recipes are well loved (like the classic Almost Five-Ingredient Pizza Spaghetti Pie) and include ideas for slow cookers, Instant Pots, and air fryers, as well as vegetarian, holiday, and party dishes — inspiration for paleo-friendly fare no matter the occasion.

PaleoHacks

Have a question? Pop it into the PaleoHack’s search bar and you’ll have answers at your fingertips. Find paleo recipes, advice on beginning a paleo diet, various resources for exercising when on the paleo diet, and more.

Favorite Resource for Paleo Diet Meal Planning

Nom Nom Paleo

It can be tough to remember what is and isn’t allowed when going paleo, so a meal planner helps take out the guesswork. This one, by Michelle Tam’s Nom Nom Paleo, includes about 150 recipes, along with step-by-step photos, that are gluten-free, soy-free, and refined sugar-free. The app can be downloaded on the App Store for $5.99.

Favorite Paleo Diet App

Stupid Simple Paleo Tracker

This app provides a handy visual food list (so there are no questions about what’s allowed), plus a calorie and macronutrient tracker so you can better work toward your goals and chart your progress. Find it on the App Store, where it’s free with in-app purchases and has a 4.3-star rating, or through Google Play, where it’s also free and has a 3.7-star rating.

Favorite Paleo Podcast

The Paleo Solution Podcast

Robb Wolf, the author of The Paleo Solution and Wired to Eat, has a 4.6-star rating on Apple. Though new episodes stopped in 2020, if you’re just tuning in, you’ll have over 400 weekly episodes to choose from. Topics include what to eat on paleo, how to try intermittent fasting, and tips for exercising.

Additional reporting by Stephanie Bucklin and Melinda Carstensen.