For people looking to lose weight or lower their blood pressure, two different diets could help.
In a new study, published in late May in Nutrients, the keto and Mediterranean diets achieved both goals in overweight and obese participants with elevated blood pressure.
With about 40% of adults in the U.S. living with obesity and nearly half having high blood pressure—both major risk factors for heart disease and other chronic conditions—this research presents accessible dietary interventions for a large population.
But experts cautioned that one of these diets isn’t ideal for everyone, and shared guidance for choosing the right eating plan.
To compare the effects of the keto and Mediterranean diets, researchers tested them in 26 people. The participants were overweight or obese and had slightly high blood pressure or hypertension.
Researchers split participants into two groups: 15 people followed a keto diet, and 11 adopted the Mediterranean diet.
The study did not specify the foods participants ate, but it did define the levels of several macronutrients in each diet:
- Keto diet: High in protein and fat, low in carbohydrates
- Mediterranean diet: High in carbohydrates and potassium, low in sodium
Both diets involved calorie restriction, with all participants eating about 1,300 calories a day.
After three months on the diets, participants in both groups saw a drop in weight and blood pressure. People also had reductions in waist circumference, BMI, and fat mass.
The only significant difference between the diets was their effect on nocturnal dipping, or the natural drop in blood pressure while you sleep. Participants on the keto diet saw a larger drop in nighttime blood pressure, which may indicate better overall heart health.
The study’s main limitations were its short duration and small sample size. It also wasn’t randomized, meaning participants weren’t assigned to a diet by chance. Instead, they were placed on each plan based on their nutritional profile and personal preferences.
Both diets produced similar results in the study, but they’re very different.
The ketogenic or keto diet is typically high in fat and protein and low in carbohydrates. It aims to cause weight loss by inducing ketosis, when the body burns fat for fuel instead of carbohydrates.
The Mediterranean diet is high in carbohydrates—particularly whole grains, fruits, and vegetables—and lower in protein and fat from animals. It’s based on the traditional eating habits in blue zones around the Mediterranean Sea and is thought to help people live longer.
Despite their differences, both diets can help you lose weight.
On the low-carb keto diet, “you’re going to get weight loss because you’re cutting out a major macronutrient,” Sue-Ellen Anderson-Haynes, MS, RDN, spokesperson for the Academy of Nutrition and Dietetics and founder of 360Girls&Women, told Health.
The Mediterranean diet will also promote weight loss, she said, “because you are cutting out saturated fats, and you’re also including more nutrient-dense foods.”
For the study participants, the weight loss from the diets likely caused the improvements in blood pressure. “Any weight loss is going to produce this because studies have shown a direct relationship between weight loss and blood pressure,” Anderson-Haynes explained.
The low-calorie intake of both diets likely explains most of the study participants’ weight loss, but Anderson-Haynes said the nutrients and whole foods in each diet may still make a difference.
“Calorie reduction generally lends to weight loss, but weight loss is complicated,” she said. “We know that energy in, energy out is not always the magic formula.”
While both diets may help manage weight and blood pressure, experts usually recommend the Mediterranean diet over the keto diet.
While keto can cause rapid weight loss and help control blood sugar, its restrictions make it difficult to maintain long-term, Laura Acosta, DCN, RDN, LDN, an instructional associate professor in the Food Science and Human Nutrition Department at the University of Florida, told Health.
Experts also had concerns about cutting out carbohydrates, mostly because of the loss of fiber—a specific type that’s essential for weight management, heart health, the gut microbiome, and more.
“I would rate keto diet a low health quality, because you’re cutting out these fibrous foods,” Anderson-Haynes said. “They’re cutting out the types of fiber in your diet that you need to thrive on for good health.”
The keto diet also comes with several other downsides:
- Higher cholesterol, which may worsen heart health over time
- Digestive issues, such as constipation, diarrhea, and bloating
- Cognitive decline, with symptoms like brain fog and memory impairments
- Keto flu, or the side effects, like vomiting, headache, fatigue, and insomnia, some feel during the first few weeks on the diet
- Keto breath, a distinct, unpleasant odor in the mouth from chemicals produced during ketosis
The Mediterranean diet also comes with risks—such as lower iron levels and more red wine consumption—but experts said it’s not as extreme or restrictive as keto.
“No food is off limits, which is the one feature about [the Mediterranean diet] that I really appreciate,” Lisa Moskovitz, RD, CDN, CEO of NY Nutrition Group and author of “The Core 3 Healthy Eating Plan,” told Health. “All foods can fit, but we’re highlighting and prioritizing foods that we know are the most health-promoting.”
The Mediterranean diet has a number of well-researched benefits, including:
- Reducing inflammation
- Supporting heart health
- Decreasing the risk of diabetes
- Preventing certain cancers
- Improving brain health
While the Mediterranean diet can promote weight loss, Acosta said it’s not really a weight-loss diet. “It’s just a helpful way of eating,” she said. “And I think sometimes weight loss just follows naturally because it’s a type of eating that will feel really satiating.”
“Both diets can help, but I would say the strength and sustainability of the Mediterranean diet is stronger,” Acosta added.
The keto diet may be the right choice for some specific groups, Anderson-Haynes said, including people losing weight before bariatric surgery and those with epilepsy. There’s also some early research that keto could benefit people with type 2 diabetes, Acosta said.
But the Mediterranean diet can work for anyone and everyone, experts agreed.
It may not fit the foods in everyone’s culture, Anderson-Haynes noted, but simple tweaks can usually make it work. For example, Anderson-Haynes recommends snapper instead of salmon for clients in the African diaspora.
When creating a diet plan, Moskovitz recommends considering several questions:
- What are your long-term goals?
- What is realistic for you?
- What sounds good to you?
- What can you continue to follow for a lifetime?
Consulting a dietitian can also help you find a diet tailored to you and your goals, whether that’s losing weight, lowering blood pressure, or something else.
“A healthy diet is something that you can stick to long-term,” Anderson-Haynes said. “Working with an expert is going to get you there.”
