The key differences between the paleo and keto diet, and which one nutritionists recommend

• While the keto diet may help you lose weight faster, it isn't as sustainable as the paleo diet, according to dieticians.
• The paleo diet emphasizes eating unprocessed foods, which means eliminating bread, grains, and legumes and eating a high-protein diet.
• The keto diet emphasizes eating a low-carb, high-fat diet in order to achieve a fat-burning state known as ketosis.

Leading a healthy lifestyle means eating the right foods, but the foods that are right for you may not be for another. This individualized approach has led to a flood of different trends. Among them are two notable diets:

• Paleolithic diet: Aka the "paleo diet" or "caveman diet", a nutrition plan originally based on the eating patterns of our human Paleolithic era ancestors who hunted and gathered for food. This diet has morphed into one that resembles many other low-carbohydrate diets.
• Ketogenic diet: Aka the "keto diet", a high-fat, moderate-protein, and extremely low-carbohydrate diet that aims to achieve a fat-burning metabolic state called ketosis.

Both diets restrict refined sugars, but on the paleo diet, most calories come from protein. For the keto diet, they often come from fat. In general, there is no definitive answer on which diet is inherently better.

Important: Before starting a diet or eliminating food groups, consult with a registered dietician, nutritionist, and/or a doctor.

Ultimately, it comes down to what works for you, since everyone responds differently to different foods, says Sarianne Madsen, RD, CSP, pediatric and ketogenic dietitian at UCSF Benioff Children's Hospital San Francisco.

According to Madsen, "The focus for health should be on achieving a lifestyle change of increasing whole foods that minimize blood sugar spikes and crashes, not on short-term restrictions and yo-yo dieting."

Here are the tenets, benefits, and disadvantages of the paleolithic and ketogenic diets including weight loss and overall health.

What is the paleolithic diet?

There is limited evidence for the exact diet of our Paleolithic ancestors. It greatly varied depending on geography and food availability, so the paleo diet is only a modern interpretation of their eating pattern that is adapted to present-day lifestyles, with an overlay of current beliefs.

However, "just because they ate a certain way doesn't mean it is optimal for modern-day humans," says Ayana Davis, MS, registered dietitian nutritionist at UCSF Cancer Center. Here are the main principles of the paleo diet:

• Going back to our prehistoric ancestors' diet: The paleo diet encourages the consumption of foods that can be obtained through hunting, gathering, and fishing. This includes fruits, vegetables, organ meat and fatty cuts, fish, nuts, and seeds.
• Limiting food staples from agricultural practices: Our ancestors relied on simple stone tools, so they didn't grow food and raise livestock yet. Therefore, foods such as dairy products, legumes, and grains, must be kept to a minimum.
• Rejecting modern-day processed foods: Modern food systems and production techniques that led to the increase of processed, refined, and sodium-heavy foods are thought to cause the rise of chronic illnesses and various diseases. Only lean meat from grass-fed animals is allowed, and canned meat, bacon, hotdogs, and processed oils are restricted.

"A common misconception about paleo is that it is low-carb because it restricts grains, when in fact, paleo includes fruits and vegetables which can add up quickly to a moderate or even high daily carbohydrate intake," says Madsen.

However, some people who practice the paleo diet may choose to limit carbs if that's part of their individual nutrition goals.

What is the ketogenic diet?

People who want to lose weight quickly often try the keto diet, but it takes two to three weeks to start ketosis. This diet quickly became a hugely popular trend, but there's little evidence about its purported benefits. Here are the fundamentals of the keto diet:

• Low consumption of carbohydrates: The keto diet severely limits carbohydrates to less than 50 grams per day. For reference, this amount is less than four slices of bread's worth. You can only eat potatoes, rice, baked goods, and pasta in restricted amounts.
• Moderate amounts of protein: Seafood is a great source of protein for the keto diet, but you can also incorporate lean meat, yogurt, nuts, and seeds. Protein helps you stay full longer and is associated with weight loss and management. However, too much protein can limit the ability to achieve nutritional ketosis.
• High in fat: About 60%- 80% of the daily calories should come from fat, but the type of fat matters. Unsaturated and omega-3 fats are the healthiest, which can be found in seafood, olive oil, avocado, nuts, and seeds.

"People should have a discussion with their doctors or dietitians to decide if the ketogenic diet is safe for them based on their individual health conditions," says Davis. Following diet fads without consulting health professionals may result in rapid weight loss fluctuation (or yo-yo dieting), which is associated with increased mortality.

Is the keto or paleo diet better?

There is no conclusive answer on which diet is healthier because it depends on each individual.

"The ketogenic diet can help achieve weight loss faster than the paleolithic diet, but as a lifestyle, the paleolithic diet is easier to follow long term and therefore achieve long-term weight loss success," says Davis. However, on the paleo diet, an individual might not get enough calcium and fiber due to the limitation on dairy, legumes, and whole grains, she says.

Since the 1920s, the keto diet has been used for patients with epilepsy for its therapeutic benefits, and more recently, for type 2 diabetes, brain tumors, and Alzheimer's as well, says Madsen.

The keto diet is thought to help with weight loss because it can control appetite, hunger, and satiety, but there is limited research on the matter. If the diet isn't properly planned and monitored, it won't be sustainable. There may be a risk of micronutrient deficiencies, lack of fiber that may lead to constipation, and other drawbacks.

Insider's takeaway

The Paleolithic diet is a modern interpretation of ancient Paleolithic ancestors' dietary patterns. Only foods that can be obtained through hunting and gathering are allowed, such as fruits, vegetables, and lean meat, which restricts the consumption of dairy, legumes, and grains.

Meanwhile, the Ketogenic diet severely limits carbohydrates and favors fat to achieve ketosis, the metabolic state where the body gets its energy from fat. It is beneficial for people with certain health conditions, and if properly managed, planned, and monitored by a trained medical professional, it can be followed for long periods of time.

"Committing to the ketogenic or paleo diet takes a person that is willing to learn, put effort into, and adapt to these lifestyle changes," says Madsen. Any long-term diet plans should be managed by a physician or registered dietitian to meet individualized macronutrient and micronutrient goals, she says.

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