If you’re health conscious, you’ve probably heard of the paleo diet. The diet has its roots in the Paleolithic era, which stretched from about 2.5 million to 12,000 years ago. The paleo diet exploded into the mainstream in 2011, and it’s been the fastest growing diet trend since, with strong ties in the CrossFit community.
Paleo should not be confused with the ketogenic diet, a very low-carbohydrate diet developed in the 1920s to curb childhood epilepsy. Recently keto, as the ketogenic diet is often called, has gained more widespread popularity as a way to lose weight quickly, reverse serious health problems, and boost energy levels. The keto diet has a number of celebrity followers including Kim Kardashian and LeBron James, while Tim McGraw and Jessica Biel are advocates of Paleo.
Paleo and keto have some key similarities, but they’re also different. Keep reading to learn what makes paleo and keto unique, and to discover the pros and cons of trying either.
The Paleolithic Diet
Modern people eat radically differently than our hunting-and-gathering ancestors did 12,000 years ago when all calories likely came from wild game, nuts, berries, and vegetation. Processed foods—such as bread, snacks, cereal, and soda—make up 67% of the average American’s calories. On average, 15% of modern Americans’ daily calories come from refined sugar, which contains no nutrients.
While most Paleolithic hunters and gatherers probably ate a large shopping bag full of highly nutritious wild greens every day, modern Americans eat few fruits and vegetables and almost no wild foods. Our meat is much higher in saturated fat than wild game because farmers fatten livestock with grain and corn. Today, most Americans eat large amounts of highly processed soybean and corn oils, which are low in omega-3 fatty acids and high in omega-6 fatty acids. Modern fruits and vegetables contain far fewer vitamins and minerals than they did even 100 years ago because our produce is grown in depleted soils, and crop types are selected to survive long-distance transport and long-term storage. According to one study, we’d need to eat eight oranges to get the same amount of vitamin A our grandparents got from eating one.
Humans have been farming since the Neolithic Revolution, which according to archaeologists took place about 10,000 years ago. But paleo enthusiasts believe our bodies have not yet evolved to thrive on cultivated grains, legumes, and dairy products. They also eschew refined sugar, a cheap bulk commodity, and processed foods, instead, striving to emulate the diet humans ate before farming.
Paleo followers don’t all agree on what to eat. For example, some eat potatoes, sweet potatoes, starchy vegetables, and salt, while others don’t.
A sample paleo eating plan may look like this:
- Breakfast: Vegetable omelet, berries, coffee with coconut milk
- Snack: Handful of nuts
- Lunch: Chicken salad dressed with olive oil
- Snack: Apple slices with almond butter
- Dinner: Grass-fed steak with steamed vegetables and a baked sweet potato
Anecdotally, many people, including well-known advocate Mark Sisson, founder of the website Mark’s Daily Apple, report paleo has improved their health. He contends that ditching grains and sugars is the key to a healthy life.
One small study suggests paleo may improve glycemic control and cardiovascular risk factors for type 2 diabetics better than the diet currently recommended by U.S. government dietary guidelines. A longer-term European study of obese postmenopausal women compared paleo to a diet that meets Nordic nutritional standards. Paleo eaters lost more fat, had bigger decreases in waist circumference, and had larger improvements in their triglyceride levels than those who ate the Nordic diet.
There’s no real danger to trying paleo, although it can be expensive if you stick with wild-caught and grass-fed meats and organic vegetables and oils. Moreover, some environmental activists warn it’s not an environmentally friendly diet because it relies heavily on resource-intensive grass-fed meats as well as imported coconut products and exotic nuts.
It’s also worth noting that not everyone agrees with key paleo tenets, namely that the paleo diet mirrors what people ate in the Paleolithic era, that humans have not evolved to eat cultivated foods, or that paleo is the healthiest way to eat. Diets in the Paleolithic era actually varied widely by geography, according to experts. For instance, the Arctic Inuit ate mainly meat and fish while the !Kung of the African Kalahari Desert ate mostly nuts and seeds. Moreover, few modern paleo followers actually eat hunted game or wild vegetation. Furthermore, there’s evidence humans have evolved to eat cultivated foods. For instance, we developed lactose tolerance within the past 10,000 years, making it possible to digest dairy products. Finally, critics of paleo point out that the healthiest populations in the world thrive on diets consisting of large amounts of complex carbohydrates (including vegetables, grains, and legumes), moderate amounts of meat, and medium amounts of fat.
The Ketogenic Diet
Starvation temporarily cures epilepsy, a fact known since ancient times. Before anticonvulsant medications became available in the twentieth century, epileptic children were commonly given only water for 10 days or more to treat severe seizures.
In the 1920s, Dr. Russell Wilder discovered that feeding epileptic children a diet extremely low in carbohydrates and high in fat mimicked the effects of starvation and reduced or eliminated seizures. He called this diet a ketogenic diet because it forces the liver to burn fat instead of carbohydrates. In the process, the liver releases organic compounds called ketones into the bloodstream, which the body uses as fuel in place of glucose.
A standard ketogenic diet contains 5% carbohydrates, 75% fat, and 20% protein. To ensure the body stays in ketosis (fat-burning mode), followers of the diet must eat about 50 grams of carbohydrates or less per day, the equivalent of about a cup of brown rice.
The ketogenic diet is still used to treat drug-resistant epilepsy, while clinical trials suggest it may be beneficial for a number of other neurological disorders including headaches, neurodegenerative diseases, neuropathic pain, sleep disorders, bipolar disorder, autism, and brain cancer.
Recently, people have embraced keto as a way to lose weight and restore health. Anecdotally, many converts report remarkable benefits.
- Lynne Ivey credits the diet with helping her lose 205 pounds and end decades of yo-yo dieting.
- Leanne Vogel, author of The Keto Diet and creator of the blog Healthful Pursuit, writes that keto helped her end a long struggle with menstrual irregularities, adrenal dysfunction, hypothyroidism, and low hormones.
- In a 24-week study, keto was found to be safe and effective as a weight-loss therapy for obese individuals.
Keto is not for everyone. It requires dedication to keep the body in ketosis, and it’s difficult even for those who stand to benefit most. In trials of epileptic children, the majority are not able to stay on the restrictive diet long-term. Many people experience a difficult transitional period called the “keto flu,” which lasts for several days to two weeks as the body adjusts to burning fat instead of glucose. Headache, nausea, fatigue, and brain fog are common symptoms. Followers must be careful to drink a lot of water and replenish electrolytes with broth or a potassium supplement to avoid dehydration.
Keto and other very-low-carbohydrate diets are associated with a number of potential adverse health effects, including dehydration, digestive issues, nutritional deficiencies, kidney stones, difficulty exercising, decreased metabolism, loss of muscle mass, gallbladder problems, menstrual irregularities, bone demineralization, thyroid dysfunction, fertility issues, and more. If you’d like to try keto, it’s important to make sure the potential benefits outweigh the risks. Talk to your doctor first, especially if you have health concerns. Most experts agree keto is not an appropriate diet for pregnant or breastfeeding women, people with thyroid conditions, high-performance athletes, or children with no medical reason for being in ketosis.
Keto is not as easy to follow as paleo. Keto followers need to pay attention to consuming precise percentages of fat, protein, and carbs to keep the body in ketosis. A sample eating plan may look like this:
- Breakfast: Eggs, bacon, half an avocado, and coffee with heavy cream
- Snack: Handful of macadamia nuts or pecans
- Lunch: Salad made with lettuce, half an avocado, two hard-boiled eggs, and homemade oil and vinegar dressing
- Snack: Cup of chicken broth
- Dinner: Salmon and steamed broccoli with melted cheese
Although it’s not strictly necessary, followers usually measure the ketones in their blood, breath, or urine daily for at least the first month to make sure the liver is releasing ketones, a sign the body is burning fat instead of glucose.
Both keto and paleo eliminate refined sugar and emphasize whole foods. In that way, they may be healthier than the Standard American Diet, which is associated with a long list of adverse health conditions including obesity, cardiovascular disease, cancer, dental disease, birth defects, metabolic diseases, bone disease, and other chronic conditions. But paleo and keto aren’t for everyone. In fact, there’s really no one-size-fits-all diet.
Increasingly, research suggests the way bodies respond to food is personal and dependent on a variety of factors. Researchers at the Weizmann Institute in Israel discovered that a meal that caused a steep rise in one subject’s blood sugar hardly affected another subject’s blood sugar levels. If a subject had an allergic reaction to a certain food, such as buckwheat, he or she experienced an atypical rise in blood sugar. Subjects’ blood sugar levels were also affected by sleep and exercise patterns. Researchers are also just beginning to understand how a person’s vast and unique microbiome helps determine how foods are metabolized. The bottom line? Within an office building or a household, people may thrive on different diets.
It doesn’t hurt to experiment with different ways of eating to see which approach works best for you. But talk to your doctor before transitioning to keto since very-low-carb diets are associated with potential health risks. No matter what you decide to eat, pay close attention to how you feel. That way you can let your body guide you to the lifestyle and way of eating that best suits you.