Paleo vs Keto Diet: Which is Better for Weight Loss? (podcast)

Keto limits carbs, paleo prefers whole foods, Pegan diet is combo

Dr. Samantha Harris is an endocrinologist and weight-loss specialist at Scripps Clinic.

Keto limits carbs, paleo prefers whole foods, Pegan diet is combo

There are numerous diets and weight loss programs on the market these days and the keto and paleo diets are among the most popular.

Though there are different variations, the keto diet essentially limits carbohydrates so that the body turns to fat as its primary fuel source instead. On the paleo diet, sometimes called the caveman diet, users are encouraged to only consume foods that were available to our ancient ancestors.


In this episode of San Diego Health, host Susan Taylor interviews Samantha Harris, MD, an endocrinologist who specializes in weight management at Scripps Clinic Del Mar. They discuss how the keto and paleo diets work, what foods are allowed on each, and why only following these or any diet in the short-term can derail your long-term weight-loss goals.

Listen to the episode on how the paleo and keto diets work

Listen to the episode on how the paleo and keto diets work

Podcast highlights

What is the keto diet? (0:42)

The keto diet varies in terms of definition, but it’s essentially an eating plan that is low enough in carbohydrates that people start using fat for fuel and energy as opposed to carbohydrates.

What is ketosis? (0:56)

When people are eating low enough in carbohydrates, they can enter the state of ketosis. Even if they’re not eating, they can enter the state of nutritional ketosis. Ketosis happens when the body relies on the breakdown of fat and the byproducts of this, which is ketones, for energy, as opposed to using carbohydrates for fuel.

How do you know you’re in ketosis? (1:16)

There are a lot of ways to tell. There are mechanisms out there that can test your breath, that can check your blood, that can even check your urine. But most people are able to tell. A lot of times, they might feel thirstier. They might be urinating more frequently, even lose a few pounds pretty quickly in the first few days. It can also cause a change in tastes, like a metallic taste in the mouth or a change in your breath. It can affect your stomach sometimes, causing a little bit of nausea, decrease in appetite or energy, sometimes difficulty sleeping, especially in the beginning.

What is intermittent fasting? (1:53)

Intermittent fasting comes in a variety of different forms: the most common being time-restricted feeding, where most people will eat for an eight-hour period of time during the day, and then fast for 16 hours until the next day and continue that cycle.

During periods of fasting, especially when we’re not eating anything and we’re not eating carbohydrates, our body really has to turn to an alternative fuel source, which is fat. So it breaks down fat, which can lead to more ketones as a source of fuel and energy since we’re not really eating and don’t have that immediate source of carbohydrate.

What foods can you eat on the keto diet? (2:34)

That can vary depending on which keto plan somebody is following. But essentially, animal protein is very low in carbohydrates. Most fat sources are also low in carbohydrates. So, we're talking about things such as beef, chicken, fish, eggs; certain oils, mayonnaise, certain types of cheese and vegetables.

Some keto plans permit other foods, such as nuts and fruit, but it really depends on how strict of a low-carb plan somebody is following.

What foods do you need to avoid on the keto diet? (3:06)

Avoid anything that is really high in carbohydrates, such as simple sugars, processed sugars, juice, starches, breads, potatoes, corn, rice. Even fruits can be very high in carbohydrates and sugar, depending on the fruit type, which is why a lot of people limit those as well.

What kind of fruits would you limit on the keto diet? (3:28)

Fruits that are higher in sugar include tropical fruits, such as pineapple, grapes, bananas, mangoes, papaya. Fruits that are lower in carbohydrates include berries, such as blueberries, raspberries and strawberries.

How long do you stay on the keto diet? (3:46)

Any time somebody does a diet, it really should be an eating plan that is a permanent solution because any time someone does a temporary change in eating and then goes back to eating the way they were beforehand, they run the risk of regaining the weight that they had lost.

In general, I only recommend people follow any type of eating plan, whether it’s keto, paleo, or otherwise, if they’re really committed to it pretty much forever.

Who’s a good candidate for the keto diet and who’s not? (4:34)

A good candidate for a keto eating plan is somebody who is very motivated, enjoys the food in the plan, and wants to do it forever because really, it’s a long-term solution and not a short-term plan.

The people I usually recommend not to do it are people who for example cannot eat protein because they have advanced kidney problems. Women who are pregnant or who are nursing really should not be in the state of ketosis. It potentially has some effects on the developing fetus or on nursing of the child. Anyone with a history of eating disorders: binge-eating disorder, anorexia. Cutting out carbohydrates can worsen the cycle and make eating disorders worse in the long run.

What is the paleo diet? (5:21)

This was a very popular diet a few years back, but a lot of people still are following it as an eating plan. Essentially, it’s sort of going back to the basics as we would imagine our ancestors would have eaten, especially whole foods, unprocessed foods, but avoiding certain foods, especially dairy and grains. The diet really focuses on protein and especially lean proteins, such as fish, chicken, eggs, nuts, fruits and vegetables, including root vegetables such as cassava.

Can you eat meat on the paleo diet? (6:02)

Meat consumption on a paleo plan is considered acceptable, but generally, leaner cuts of meat are preferred. I usually recommend grass-fed meats as opposed to grain-fed meats. It really depends on your level of carbohydrates because if you’re eating foods that are higher in carbohydrates, such as fruits, carrots, more starchy type vegetables. You really don’t want to be eating very high-fat foods as well because the conjunction of high-fat and high-carbohydrate foods together can be problemsome.

Who is a good candidate for the paleo diet? (6:35)

A good candidate for a paleo plan is somebody who enjoys the foods in the plan, wants to continue it indefinitely or for at least the majority of the time. Like I said, anything that’s considered temporary then leads back to old eating habits will usually result in weight regain.

What are the health benefits of the paleo diet? (6:56)

The health benefits of eating foods that are whole, natural, high in vegetables, low in sugar are numerous.

One, it can help promote weight loss. In my clinic, I have a sample of a five-pound fat mass that I sometimes show patients who feel like five pounds isn’t a lot of weight loss. But it really is a lot. A visual demonstration can be helpful.

Weight loss is a benefit of both keto plans and paleo plans. Any diet that’s limiting calories and is easy to stick to can help people lose weight. When people lose weight, their general health and well being improve. They lower their risk of cancer, high blood pressure, heart disease, diabetes, depression, sleep apnea and dementia. It goes on and on.

What is the Pegan diet? Is it a combination of paleo and vegan? (7:50)

I haven’t yet seen that many people are following it. It seems to be essentially a paleo-type plan with a focus on plant-based foods. About 75% of daily food intake is coming from fruits and vegetables and only a small amount is coming from meat. It is more of a plant-based paleo, where you are still eliminating beans and starches, sugar, dairy foods and grain products, such as wheat.

What’s the benefit of the Pegan diet? (8:35)

The benefits are similar to a paleo or a keto-type plan when it comes to weight loss, but there is evidence that focusing on more plant-based foods might also help in terms of cardiovascular risks.

There is a lot of debate out there, but I don’t think anyone can argue that eating a lot of vegetables and whole foods and avoiding processed refined foods isn’t good for your health.

What’s the best diet approach? (9:02)

Any type of eating plan really depends on your personal preferences, what you enjoy eating, what you think you could continue in the long run because it shouldn’t be a temporary fix.

The data has shown that short-term diets usually fail in the long-term because people will regress to their prior eating habits. So definitely think about something that’s simple, that is safe, but most importantly, sustainable for you or that can be continued indefinitely.

Lightly edited for clarity

Watch the San Diego Health video on the keto and paleo diets

Watch the San Diego Health video with Susan Taylor and Dr. Harris discussing the difference between the paleo diet and the intermittent diet.

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