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

Medically Reviewed

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 assistant 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 comprised only of foods that can be hunted and gathered.

In its purest form, the paleo diet allows you to eat only 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.

You’ll lose weight because anytime you restrict entire food groups, your calorie intake tends to be lower, Dr. Sandon says. And whenever you burn more calories than you consume, you'll lose weight, she says.

The focus on lean protein, fruits, and vegetables over calorie- and sodium-rich processed foods can also contribute to weight loss, Sandon says, but she points out that the paleo diet wasn’t created to be a weight loss diet.

Note that though 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.

RELATED: What Is an Elimination or Exclusion Diet?

What Does Research Say About the Paleo Diet?

So what does the science say about the paleo diet? Some research suggests that the health claims hold water. A review analyzed four randomized controlled trials with 159 participants, and researchers 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, published in the journal Australian Family Physician in January 2016, reviewed clinical trials that explored the effect of paleo on health markers including 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 article concluded that because of the small sample sizes, short duration, and the 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 an article in response to the first review, authors Tanis R. Fenton and Carol J. Fenton, from the University of Calgary Cumming School of Medicine in Alberta, wrote a letter to the editor in which they expressed their disappointment with the review.

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.

Foods to Eat and Avoid on the Paleo Diet

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, peppers, and pumpkin
  • 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

Learn More About What Foods to Eat and Avoid on the Paleo Diet

A Sample Menu of What to Eat on the Paleo Diet

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 (virtual or not!). 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

Learn More About Where to Find Paleo Diet Recipe Inspiration and Get a Five-Day Sample Menu

Possible Risks and Benefits of Trying the Paleo Diet

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 prepacked 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. 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.

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 — foods that are organically grown, and grass-fed beef and other meats typically cost more.

For example, one model based on data sets from the United States Department of Agriculture found that a 9 percent increase in income would be necessary in order to follow the paleo diet while meeting all daily recommended micronutrient intakes (except for calcium).

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. It’s not really a new concept; instead it’s one that’s been recycled through the years, she says.

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 a locally sourced meat, whose origin and method of raising you're aware of, as a healthier option. Saturated fat from meat has been linked with an increased risk of early death.

The Australian Family Physician article mentioned above highlights potential calcium deficiency as a “significant issue” with the paleo diet. One study cited in the article, published in the European Journal of Clinical Nutrition, 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.

As previously stated, a registered dietitian can help you follow this plan safely and avoid deficiency in nutrients like calcium.

Learn More About the Possible Benefits and Risks of the Paleo Diet

If You Have Diabetes, Is Paleo a Good Choice for Blood Sugar Management?

While there’s no perfect diabetes dietsome 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 the paleo diet allows may have an adverse effect on heart health in people with diabetes, as research links eating red meat in excess to poor heart health.

 If you have diabetes and don’t moderate your red-meat intake, 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.

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 just yet. 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.

Learn More About How the Paleo Diet May Affect Type 2 Diabetes

Is the Paleo Diet Good for Heart Health?

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 cake, 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.

These are all comorbidities of heart disease.

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

Learn More About the Risks and Benefits of the Paleo Diet for the Heart

Can the Paleo Diet Help You Manage Autoimmune Diseases?

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, psoriasiseczema, 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 should you try it.

Learn More About How the Paleo Diet May Affect Autoimmune Diseases

What to Expect if You Try the Paleo Diet

You could lose weight following a Paleolithic diet — and quickly, 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 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 onto 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.

Learn More About What to Expect if You Try the Paleo Diet

Paleo Diet Resources We Love

Favorite Resources for Info About the Paleo Diet

The Paleo Diet

Loren Cordain, PhD, 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 “Is It Paleo?” to the latest research on the caveman diet.

Diet Review: Paleo Diet for Weight Loss 

Leave it to Harvard University's T.H. Chan School of Public Health to deliver 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 Blog


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 Crock-Pot, Instant Pot, and air fryer, as well as vegetarian, holiday, and party dishes — inspiration for paleo-friendly fare no matter the occasion.

Favorite Resource for Paleo Diet Meal Planning

Paleo Leap Meal Planner

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 Paleo Leap, includes 1,500 recipes that are gluten-free, grain-free, legume-free, sugar-free, soy-free, and corn-free. Also free? The app, which you can download on Google Play or the App Store.

Favorite Paleo Diet App

Stupid Simple Paleo Tracker

This app provides a handy visual food list (so there’s no question what’s allowed and what’s not), plus a calorie and macronutrient tracker so you can better work toward your goals and chart your progress. Find it on iTunes, where it’s free with in-app purchases and has a 4.2-star rating, or in the Google Play store, where it’s also free and has a 3.7-star rating.

Favorite Paleo Community


You have questions — and the vast community of paleo devotees has answers. From how to pair paleo with fasting, to psychological side effects, to why avoiding oatmeal is a must, you’ll find that connecting with like-minded members will help you feel supported.

Favorite Paleo Podcast

The Paleo Solution Podcast

Robb Wolf, author of The Paleo Solution and Wired to Eat, has a 4.7-star rating on iTunes. If you’re just tuning in and need to get caught up, 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.

For more of our feel-good podcast picks, check out our article.

Additional reporting by Stephanie Bucklin and Melinda Carstensen.

Editorial Sources and Fact-Checking

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