The Paleo Diet: How It Works, What to Eat, and the Risks
Medically Reviewed by Kelly Kennedy, RD
Obesity, heart disease, and diabetes: These are just a few of the health conditions that proponents of thePaleolithic diet, or caveman diet, blame on our sedentary lifestyles and modern diets, which are 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, Colorado, and the author of The Paleo Diet; Erin Holley, RD, of Ohio State University Wexner Medical Center in Columbus, Ohio; 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, 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 millions of 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. (1)
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You’ll lose weight because any time you restrict entire food groups, your calorie intake tends to be lower, Sandon says. And whenever you burn more calories than you consume, you’ll have weight loss, she says. (2) The focus on lean protein, fruits, and vegetables over calorie- and sodium-rich processed foods can also contribute to weight loss, though she also points out that the paleo diet wasn’t created to be a weight loss diet. (3)
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 consumption of them.
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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 truth. 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 other control diets. (4)
Still, 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 fact, in an article in response to the first review, authors Tanis R. Fenton and Carol J. Fenton, from the Cumming School of Medicine in Canada, wrote a letter to the editor in which they expressed their disappointment with the review. (5)
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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, in fact, 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 with 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
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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
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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.
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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
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 potential benefits you may 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 help lower your risk of certain diseases, like type 2 diabetes and certain cancers, she says. ( 6 )
Furthermore, the diet emphasizes exercise. Exercise is an important part of a healthy lifestyle and can help you lose or maintain your weight. ( 7 )
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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 as well as grass-fed beef and other meats typically cost more. (8)
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 adds.
For instance, the fat allowance of the diet may be problematic. “My biggest hang-up with the paleo diet is all of the saturated fats it promotes with all of 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. (9)
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If You Have Diabetes, Is Paleo a Good Choice for Blood Sugar Management?
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. ( 10 )
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But 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. ( 11 ) If you have diabetes and don’t moderate your red-meat intake, this could be a big problem, as people with diabetes are 2 times as likely to die of heart disease as people who do not have diabetes. ( 12)
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. But if you want to try the plan with the aim of helping you manage your blood sugar, be sure to clear it with your healthcare provider first.
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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.
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If you were to eat an unlimited amount of red meat (which the paleo diet technically allows), you may 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. (13) These are all comorbidities of heart disease. (14)
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.
Can the Paleo Diet Help 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, 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 should you try it.
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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.
As a 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 at one time. Holley suggests trying small incremental changes instead.
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“I’m always of the mind-set 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.
Additional reporting contributed by Stephanie Bucklin and Melinda Carstensen.
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Paleo Diet Resources We Love
Favorite Resources for Info About 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 of the info you need to get started on your paleo journey, from “Is It Paleo?” to the latest research on the caveman diet.
Leave it to Harvard to deliver an unbiased look at the research of paleo and the benefits and risks for 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 5-ingredient pizza spaghetti pie”), and include ideas for crockpot, 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
This app provides a handy visual food list (so there’s no question what’s allowed and what’s not), plus a calorie and macro 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 4.4-star rating, or in the Google Play store , where it’s also free and has a 4-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
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 our picks on feel-good podcasts, check out our article.