Can the Mediterranean Diet Help Reduce Insulin Resistance?

6 minutes read

The Mediterranean diet is one of the most well-researched diets in the U.S. Rooted in the habits and traditions of the Mediterranean region, studies provide evidence that it has powerful metabolic health benefits, including lower blood glucose levels, improved insulin sensitivity, and reduced HbA1c (a long-term measure of blood sugar) [1].

The health effects of the Mediterranean diet can last years after starting it — follow-up studies 10 years later indicate that those who consistently follow the diet have a 25% lower risk of developing diabetes [2]. But what exactly is the Mediterranean diet, and why does it help with metabolic health?

What is the Mediterranean diet?

In the 1950s, scientist Ancel Keys noticed that despite a lack of access to medical care and clean living conditions, adherents of the Mediterranean diet in Europe experienced greater life expectancy than wealthy citizens in the United States [3]. Keys argued that nutrition was responsible for many health benefits associated with the diet, such as decreased risk of cardiovascular disease, diabetes, and obesity. He also pointed out that an overall healthy lifestyle played a role as well.

Today, the Mediterranean diet is increasingly recognized by physicians and patients as not only a diet therapy but also a pathway to prevent disease in the first place.

Components of the Mediterranean diet

Inspired by the traditional eating habits of regions like southern Italy, Spain, and Greece, the Mediterranean diet consists of specific types and combinations of food that set it apart from general “healthy” diets, and make it a powerful dietary pattern for metabolic health.

Whole-grain carbohydrates such as whole wheat, millet, sorghum, sweet potatoes, and Jerusalem artichokes. Complex, unrefined carbohydrates like these provide high-energy starches, fiber that helps lower blood sugar spikes, and essential B vitamins — all of which promote metabolic health by stabilizing glucose levels, increasing satiety, and nurturing a healthy gut microbiome.
Leafy-green and nightshade vegetables like whole grains, vegetables contain fiber and also have phytonutrients, plant compounds that have anti-inflammatory and antioxidant effects. Research suggests that eating 400 grams (approximately 5 cups) of vegetables a day with 1.25 cups of citrus fruits or berries is associated with better glycemic control, significantly lower HbA1c values, and decreased waist size [4].
Legumes such as nuts, beans, and chickpeas offer a great source of fiber and protein. As the building blocks of protein, amino acids in legumes often complement those found in whole grains — i.e., the amino acids missing in carbohydrates are found in the legumes. A combination like hummus and pita or yogurt and nuts can offer most of the amino acids we need in one meal. Legumes should be incorporated daily because, unlike red meat and processed foods, they lack saturated fat and still contain a lot of protein when paired with whole-grain carbohydrates or dairy. As a low-glycemic food, legumes naturally don’t contain a lot of sugar and are associated with better glycemic control and lower risk of Type 2 diabetes [5].
While whole grains and legumes provide plant-based protein, moderate amounts of fish and poultry are high in bioavailable protein, meaning the protein is more easily digested and absorbed. Cold water fish specifically is a great source of omega-3 fatty acids, another anti-inflammatory and insulin-sensitizing compound. In the Mediterranean diet, fish and poultry foods are eaten a few times a week with one serving size being 3 to 4 ounces, or roughly the size of the palm of your hand.
The Mediterranean diet is low in saturated fats, which have historically been demonized for their association with cardiometabolic health problems and increased risk of mortality. Recent research, however, suggests that the effect of saturated fats on health is more nuanced, and that the source of the saturated fat and what you eat it with matters. For example, cheese and butter — both dairy products that contain saturated fats — have very different overall nutrient profiles and, in turn, metabolic impacts. In other words, it’s not just saturated fats that affect the risk of cardiovascular disease (CVD). The complete makeup of a food, including its fatty acids, proteins, and trace vitamins/minerals — and the chemical interactions between those elements — plays a crucial role in the food’s nutritional and health effects, including how much it changes your risk of CVD [6]. In fact, studies have found that butter has a greater impact on LDL cholesterol (the “bad” cholesterol) than cheese, even when they have the same amount of saturated fat [7]. Likewise, lean, grass-fed red meat does not seem to have the same negative impact as higher-fat, processed red meat [8]. In addition, research has found that pairing any of these with sufficient fiber from fruits and vegetables appears to reduce the instances of cardiovascular disease [9].

The takeaway? Moderate — but don’t eliminate — saturated fat, and choose sources like lean, grass-fed red meat and dairy fats like yogurt and cheese. Where possible, replace butter with extra-virgin olive oil.

Fats to incorporate in the Mediterranean diet include extra-virgin olive oil, one of the central components to Mediterranean cooking. Compared to regular olive oil, extra-virgin olive oil is abundant with phenols, scavenger-like antioxidants that seek out and retrieve compounds that contribute to inflammation, narrowing arteries, and high blood pressure [10]. Additionally, mono– and polyunsaturated fats in extra-virgin olive oil amplify the anti-inflammatory effects of the phenols and omega-3 fatty acids by stopping the release of inflammatory markers [11]. Studies show that replacing butter with olive oil lowers risk for Type 2 diabetes and improves glucose metabolism [12]. The next time you’re cooking, baking, or preparing to eat, consider switching butter for olive oil to promote these metabolic effects.

How the Mediterranean diet affects metabolic health

Collectively, eating vegetables, legumes, and whole grains can help regulate blood sugar and enhance metabolic health. But specific ingredients like fiber, phenols, and mono- and polyunsaturated fats have been shown to individually produce these changes too. Researchers today are still trying to understand how these components — individually and collaboratively — generate the metabolic effects we see.

1. Stabilizes blood sugar

Fluctuating blood sugar levels can lead to poor metabolic health and a higher risk of developing diabetes. Nutrition is one of the Four Pillars of metabolic health that can help stabilize blood sugar — and research suggests that people who follow the Mediterranean diet have a 20% lower risk of developing Type 2 diabetes. Components within the diet work together to reduce blood sugar — and subsequently diabetes risk — in numerous ways.

A large-scale clinical trial called the PREDIMED study revealed that the Mediterranean diet, enriched with extra virgin olive oil and nuts, reduced risk for Type 2 diabetes by 52% compared to a low-fat diet [13]. Sub-studies suggest that phenolic compounds in extra virgin olive oil and nuts are responsible for lowering blood sugar and HbA1C.

Fiber found in vegetables, whole grains, and legumes, can produce similar blood sugar-lowering effects because it slows digestion and absorption, minimizing massive glucose spikes and crashes [19]. Monounsaturated fats also help lower blood sugar by making cells more sensitive to insulin and accelerating its ability to help glucose get absorbed [14].

Beyond these immediate effects, the PREDIMED study indicates that the Mediterranean diet’s effects on blood sugar last in the long run — participants who followed it were still at reduced risk for diabetes 10 years later, suggesting these components play an essential role in regulating blood sugar over time.

2. Reverses insulin resistance

Insulin resistance occurs when the hormone insulin becomes less effective at helping blood sugar get absorbed from the bloodstream and into cells. Fortunately, the Mediterranean diet is rich in foods that can help reverse insulin resistance. The mono- and polyunsaturated fats in foods like extra-virgin olive oil, nuts, and seeds have two effects that sensitize cells to insulin and clear sugar from the blood [15].

The first way is through decreasing the release of inflammatory markers from fat tissue. Inflammation tends to decrease insulin sensitivity, but by clearing the markers that create the inflammatory response, mono- and polyunsaturated fats let insulin do its job better.

The second way is that mono- and polyunsaturated fats stimulate insulin release, allowing more insulin into the bloodstream to clear glucose. So not only do the fats promote insulin release, but they also make it more effective at getting glucose absorbed.

3. Promotes weight loss

One of the most common outcomes of high blood sugar and insulin resistance is obesity. In addition to lowering blood sugar and fighting insulin resistance, the Mediterranean diet has been shown to support weight loss.

According to studies, adhering to the diet is associated with lower risk of weight gain and reduced risk of overweight/obesity, and follow-ups indicate similar results 6-20 years after first starting the diet [16]. Some mechanisms behind the reduced risk for weight gain are the presence of fiber in grains and vegetables, which help to promote satiety, and replacing saturated fats with mono- and polyunsaturated fats [17].

Despite low-carb diets showing moderate success with weight loss, they are not always as nutritious or sustainable as Mediterranean diets. With these diet types, it’s easy to lose out on key nutrients such as fiber in whole grains and phenols in legumes, and people often find it difficult to stick to these long-term.

4. Reduces costs

The Mediterranean diet doesn’t just benefit your metabolic health — it can help you save money on groceries and health-related expenses as a whole. A recent 2023 study from Australia suggested that people who eat a Mediterranean diet could save $1,500 dollars annually compared to those who eat a Western diet [18]. The key difference stems from purchasing more whole grains, vegetables, fruits, lean proteins, and plant-based ingredients instead of highly-processed foods high in sugar, sodium, and saturated fat.

In addition, government-sponsored programs that allow doctors to prescribe fruits and vegetables to patients — also known as Food as Medicine programs — are thought to be able to save billions in healthcare costs. Following the Mediterranean diet, then, shows how a simple switch in food choice in the grocery aisle can reap big savings in both your wallet and health, making you more metabolically healthy and at lower risk for chronic disease later in life.

How to incorporate the Mediterranean diet into your routine

Switching up your whole lifestyle at once can be a challenge. Luckily there are a few routes you can take to embrace and amplify the effects of the Mediterranean diet while also not drastically changing your everyday living. Slowly you can work towards converging all these routes together to perfect the Mediterranean diet lifestyle in your own way.

Create a metabolically healthy routine with some of the following additions or simple swaps:

Make the ultimate insulin resistance-fighting snack by grabbing a handful of nuts for on-the-go, or pair 1 cup of polyphenol-rich vegetables with fiber-filled hummus.
Reduce inflammation associated with insulin resistance by replacing butter with extra virgin olive oil to incorporate poly- and monounsaturated fats that will help clear inflammatory markers.
Slow and reduce blood sugar spikes by adding fibrous legumes like lentils or chickpeas to a garden salad or soup.
Swap processed meats for fatty fish, chicken, or plant-based proteins at dinner.
Enjoy a nutrient-rich dessert of 1 cup of fresh citrus fruits to satisfy the sweet tooth while also avoiding highly processed sweets and added sugars that can trigger blood sugar spikes.

Takeaways

The Mediterranean diet consists of whole-grain, fiber-rich carbohydrates; leafy-green and nightshade vegetables; citrus fruits and berries; legumes; fish and poultry; and mono- and polyunsaturated fats.
The Mediterranean Diet is made up of powerful food groups that can regulate blood sugar and reverse insulin resistance. Together, these compounds can have long-lasting effects like reducing risk for diabetes, obesity, and cardiovascular disease.
While nutrition is a central component of the Mediterranean Diet, it isn’t the complete picture. Exercise and wellness practices are just as essential to overall metabolic health and will amplify the effects of the nutrition changes.
Adapting a new lifestyle all at once is hard. Start by incorporating elements of the Mediterranean diet to your existing routine — for example, finding metabolically healthy alternatives or substitutes to your favorite meals.

References:

Written by: Michelle Severs, MS

Reviewed by: Emily Johnson, MSc RD

Table of Contents

What is the Mediterranean diet?
How the Mediterranean diet affects metabolic health
How to incorporate the Mediterranean diet into your routine
Takeaways

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