Both the Mediterranean diet and the keto diet claim health benefits and weight loss—but which is better?

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Mediterranean Chickpea Quinoa Bowl

One promotes meat and cheese; the other pushes plants. Can two vastly different diets both be healthy? We take a deep dive into what the research says about the Mediterranean diet versus the keto diet.

The Mediterranean diet and the keto diet have been around for decades, but new health claims are always popping up about both diets. We summarize the pros and cons of each, discuss which foods are and aren't allowed, and note the health benefits associated with adhering to each style of eating.

What is the Mediterranean diet?

The Mediterranean diet is more of a lifestyle than a diet. Its name is a reference to the traditional eating pattern of people living in countries bordering the Mediterranean Sea. Although people in countries like Italy and Greece have been eating this way for centuries, the Mediterranean "diet" wasn't popularized until the 1960s, when a group of researchers noted that people in that area of the world were exceptionally healthy and had a lower risk of many lifestyle diseases compared to Americans.

So what does the Mediterranean diet look like? It includes an abundance of fruits, vegetables, whole grains, beans, legumes and healthy fats; a moderate amount of chicken, fish, eggs and dairy; and limited amounts of red and processed meats, added sugars and processed foods. Enjoying meals with others, having an occasional glass of red wine and being physically active most days are also components of the Mediterranean diet.

What is the keto diet?

The ketogenic ("keto") diet was developed in the 1920s as a treatment for epilepsy. It's a high-fat, moderate-protein, low-carbohydrate diet that has since been analyzed for weight loss, diabetes, cancer, Alzheimer's disease and more. The keto diet is characterized by a very low carbohydrate intake, with less than 5% of all calories coming from carbs. When carbohydrate intake is extremely low, the body begins to break down fat for energy through a process called ketosis. The liver turns fat into ketones, which are used for energy until you start eating carbs again.

The main foods that make up a keto diet include meat, fish, cheese, eggs, oils, avocados, butter, cream, nuts, seeds and low-carb vegetables. Higher-carb vegetables, most dairy, grains, beans, fruit and processed foods are limited or eliminated since they drive up carb intake.

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Pros and cons of each diet:

The cons of the Mediterranean diet:

Because the Mediterranean diet is so liberal, the lack of structure may make it hard for some people to follow. The Dietary Guidelines for Americans include a Healthy Mediterranean-Style Eating Pattern to address this, which provides serving sizes and calorie counts. Another con is that it may be time-consuming to prep meals and potentially expensive, although arguably no more time-consuming or expensive than the keto diet.

The pros of the Mediterranean diet:

On the flip side, the lack of structure in the Mediterranean diet is a pro for many. There are no restrictions and no calorie counting. It's simply about eating more of some foods and less of others. That often makes it much easier for people to adhere to than a hugely restrictive diet that may not be manageable in the long term.

The cons of the keto diet:

While the ketogenic diet can lead to rapid weight loss, it does have some downsides. As the body switches from burning carbs for fuel to burning fat for fuel, it enters ketosis, which may cause you to experience the "keto flu"—which feels like the actual flu. The keto diet also requires planning, and may require the help of a registered dietitian or other nutrition expert to ensure you are following it correctly. And because it's a highly restrictive diet, very few people are able to eat keto forever—which may lead to gaining back some of the weight lost.

Also, no one knows the long-term effects of consuming a very high-fat, low-carb diet. The Dietary Guidelines for Americans recommend eating 25-35% of calories from fat, 10-30% from protein and 45-65% from carbohydrates. On a ketogenic diet, 80% of daily calories are from fat, 15-20% are from protein and less than 5% are from carbohydrates.

The pros of the keto diet:

The keto diet can help you lose weight quickly, lower blood sugar and improve insulin sensitivity. And you don't have to count calories to do it. By eliminating food groups, you automatically reduce calories, leading to weight loss. Eating a high-fat diet increases feelings of satiety, while increased protein contributes to weight loss by suppressing appetite and boosting metabolism (although keep in mind that adding protein to any diet will do that). Finally, it also appears to outsmart ghrelin, a hormone that tells your brain you're hungry, which typically rises when people diet and lose weight: a study in the European Journal of Clinical Nutrition found that when people followed the ketogenic diet for weight loss, ghrelin was suppressed. That's good news for people who tend to give up dieting because they feel hungry all the time.

Is either diet considered healthy?

The Mediterranean diet overview:

The Mediterranean diet is associated with reduced risk of cardiovascular disease, diabetes, some cancers and Alzheimer's disease. It's also linked to longer life. The 2018 PREDIMED Study showed that, compared to a low-fat diet, when people at risk for diabetes and heart disease followed a Mediterranean diet supplemented with olive oil or nuts, both groups had lower rates of heart attack and stroke. Interestingly, participants consumed more fat than the Dietary Guidelines recommend—but the fats were omega-3s, including olive oil, nuts and fatty fish like salmon.

A diet high in omega-3s, antioxidants and polyphenols—such as the Mediterranean diet—helps lower inflammation, which is linked to obesity, heart disease, cancer and diabetes, among other conditions. (This may be part of the reason the diet is linked to better cognitive function as one ages.) Additionally, fiber from fruits, vegetables, whole grains and beans provides prebiotics, which is food for the gut bacteria that keep your microbiome healthy, thereby lowering inflammation.

Herby Mediterranean Fish with Wilted Greens & Mushrooms

The keto diet overview:

On the flip side, saturated and trans fats, processed foods, excessive sugar, refined carbohydrates and red and processed meats increase inflammation in the body. One potential danger of the keto diet is consuming large amounts of meat, cheese, eggs, butter and bacon. While long-term studies on keto are lacking, long-term research has linked red and processed meat to colon cancer and heart disease.

Because keto is very low-carb, it nixes most plant-based foods like fruits, vegetables, whole grains and legumes, which studies show are linked to reduced inflammation and better health outcomes.

Consuming too few carbohydrates long-term could also potentially shorten your lifespan, according to a 2018 meta-analysis showing that eating less than 40% of calories from carbohydrates was associated with higher mortality—particularly when carbs were replaced with animal fat or protein, rather than with plant-based protein or fat. For all of these reasons, we really wouldn't recommend the keto diet.

Mediterranean vs. Keto: What's Allowed & What's Not

A quick list of what you can—and can't—eat on the keto diet.

Mediterranean Diet vs. Keto chart
  • Clarify your goal. Are you trying to lose weight, decrease your risk of heart disease, improve your blood sugar, or something else?
  • How much work are you willing to put in? The keto diet will take more planning to ensure you stay within the recommended carb range. Going out to eat and traveling also prove more difficult on a keto diet.
  • What does your health care provider recommend? Before trying any diet, consult with your doctor and/or a registered dietitian to determine the best fit based on your goals and current health status.
  • How long can you keep up with it? While the keto diet leads to rapid weight loss, most people can't keep up keto forever, due to the extreme restrictions. Remember that if you can't continue eating a certain way forever, you won't see the results forever.
  • If following a keto diet, choose heart-healthy fats most of the time, like fatty fish, nuts, seeds, olive oil and avocados. For reduced inflammation and better health outcomes, be restrained when it comes to red and processed meats, butter and cheese.

The bottom line

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