Obesity has become a worldwide epidemic affecting more than 300 million people, including nearly one-third of American adults. As obesity has increased, so has type 2 diabetes.
Considered a disease of minor significance in the 20th century, type 2 diabetes is now a major threat to human health, afflicting 150 million people worldwide, and its incidence is projected to double by 2025.
So close is the relationship between obesity and type 2 diabetes that researchers have coined a new term to describe it: diabesity.
The fact that both obesity and type 2 diabetes have so recently and drastically increased suggests that both result from changes in our lifestyle that serve us a recipe for ill health:
Our diet has shifted to emphasize foods with low nutrient density
(supplying excessive calories in comparison to the nutrients they
Larger portion sizes
Less physical activity
Fortunately, both diet and exercise are within our control, making obesity and type 2 diabetes largely preventable.
Several epidemiological (population) studies have now shown that a Mediterranean diet offers significant protection against weight gain, particularly abdominal weight gain, which has been shown to promote type 2 diabetes. A recent review of the research, published in The Journal of Nutritional Biochemistry, (Schröder H.) explains many of the reasons why.
Fiber: the Mediterranean diet is rich in plant foods providing a variety of both soluble and insoluble dietary fiber.
Not only do fiber-rich foods require more chewing, thus slowing the rate at which food is consumed, they produce a feeling of fullness with fewer calories.
When fiber is present in a meal, the small intestine secretes peptides, such as cholecystokinin, that signal satiety to the brain. Legumes and nuts, two fiber-rich staples in the Mediterranean diet, have been shown to greatly increase the secretion of cholechystokinin.
Healthy Fats: A Mediterranean diet is rich in healthy unsaturated fats from olive oil, cold water fish, nuts and seeds.
Olive oil, a hallmark of the Mediterranean diet, is used for cooking and to add flavor to legumes, salads and vegetable dishes. Some evidence suggests that oleic acid, the predominant fatty acid of olive oil, is associated with lower insulin resistance.
Research has shown that replacing saturated fat with olive oil in the diet of obese men produces significant loss of both weight and body fat after just 4 weeks. In abdominally obese women, olive oil has been shown to increase the rate at which fat is oxidized (burned) after meals.
Plus, in the Mediterranean diet, olive oil is used to dress vegetables and legumes, which are rich in nutrients and fiber, but very low in calories.
The type of fat in the diet affects the composition of cell membranes. Saturated fats make cell membranes less permeable and receptive to signals from messenger molecules such as insulin, while the omega-3-fatty acids supplied by cold water fish, walnuts and flaxseed render cell membranes more flexible and receptive.
Nutrient-density: A Mediterranean meal typically begins with salad as a first-course-a meal plan that has been shown to increase feelings of fullness and, consequently, reduce calorie intake by 12% in comparison to meals without salad as a first course.
Moderate red-wine consumption: A glass of red wine often accompanies lunch or dinner in the Mediterranean.
In animal research, voluntary red wine consumption resulted in reduced calorie intake and prevented weight gain in rats on a high-fat diet, but whether a specific component in red wine causes these effects or if the effects are the same in humans is not yet known.
In human population studies, moderate alcohol consumption has been shown to enhance insulin sensitivity and increase levels of adiponectin, a signaling molecule that stimulates cells’ burning of both fatty acids and glucose (sugar).
Antioxidants: A Mediterranean diet provides an abundance of antioxidant-rich fruits and vegetables.
Not only has consumption of fruits and vegetables been shown to reduce risk of type 2 diabetes in several population studies, but blood levels of antioxidants have been found to be higher in persons following a Mediterranean diet.
In addition to vitamin antioxidants such as beta-carotene, E and C, the characteristic foods of the Mediterranean diet provide a wide variety of phenols with potent, synergistic antioxidant activity.
Since oxidative stress (damage by free radicals) plays a crucial role in the development of insulin resistance and beta cell dysfunction, a Mediterranean diet is highly protective against type 2 diabetes. (Beta cells are responsible for the production of insulin.)
Following an antioxidant-rich Mediterranean diet has been shown to significantly decrease insulin resistance in patients with the metabolic syndrome, and even short-term administration of virgin olive oil has been found to decrease several markers of oxidative stress.
Magnesium: Vegetables, legumes and nuts-key components of the Mediterranean diet-are rich sources of magnesium, which is an essential co-factor in enzymes required for cellular energy production.
Studies have linked insufficient magnesium with increased incidence of type 2 diabetes.
Whole grains: High consumption of whole grains, which are rich in both fiber and magnesium, is another characteristic of the traditional Mediterranean diet.
Population studies consistently show a protective effect of cereal fiber on insulin sensitivity and risk of type 2 diabetes. Furthermore, the fiber provided by whole grains delays the emptying of stomach, slowing the digestion and absorption of food, which in turn slows the rate at which glucose (sugar) passes into the bloodstream and reduces insulin levels.
By simply enjoying the healthy Mediterranean way of eating espoused by The World’s Healthiest Foods, you will naturally receive high amounts of dietary fiber, antioxidants, magnesium and health-promoting monounsaturated and omega-3 fats.
And because, this diet is characterized by nutrient-dense foods, which supply fewer calories overall, it automatically promotes a healthy weight, preventing weight gain and lessening your risk of obesity and type 2 diabetes.
Schroder H. Protective mechanisms of the Mediterranean diet in obesity and type 2 diabetes. : J Nutr Biochem. 2007 Mar;18(3):149-60. Epub 2006 Sep 11. PMID: 16963247