Study: Low-cal Mediterranean diet, exercise cut diabetes risk by 31%
1 of 3 | A low-calorie version of Mediterranean diet combined with an exercise program and “modest” weight loss can reduce type 2 diabetes risk by 31% over a more typical MedDiet, according to a Spanish study released Monday. Photo by Jep Gambardella/Pexels
Consuming a low-calorie version of a “Mediterranean diet” rich in fruits, whole grains and extra virgin olive oil — but light on meat — can help provide a big reduction in the risk for type 2 diabetes, according to a study published Monday.
In fact, when combined with a program of increased physical activity and even a “modest” amount of weight loss, sticking to an “energy-reduced” version of the Mediterranean diet slashed type 2 diabetes risk by 31% over a more typical version, a team of Spanish researchers reported in a new study in the Annals of Internal Medicine.
It’s long been known that the “MedDiet,” which by definition not a “low-fat” plan, has a clear effect in reducing various illnesses such as cardiovascular disease, neurodegenerative diseases, including cognitive impairment and Alzheimer’s disease, and even in preventing some types of cancer.
It is generally defined as a meal plan that includes plenty of fruits, vegetables, whole grains, potatoes, beans, nuts and seeds, with olive oil serving as a primary fat source. Many versions also include low to moderate amounts of “energy dense” foods like dairy products, eggs, fish and white meat, such as poultry.
Its effect on preventing type 2 diabetes, or T2D, has been less extensively studied, but now a team of scientists organized by Spain’s national Carlos III Health Institute say they have documented a strong correlation between lower rates of T2D and reduced consumption of the energy dense foods frequently found in a MedDiet.
In reaching their conclusions, the authors analyzed the health records of more than 4,700 Spanish adults aged 55 to 75 years, who had high T2D risk factors, such as being overweight or obese but with no prior cardiovascular diseases or diabetes.
They consumed an energy-reduced version of the relatively high-fat typical MedDiet that had 30% fewer calories and only limited amounts of meat, sugar-sweetened beverages and other ultra-processed foods, while substituting higher levels of nuts and extra virgin olive oil.
They were also put on an intensive lifestyle program that emphasized physical activity (such as walking 45 minutes per day or equivalent) and weight-loss goals backed by behavioral support.
Meanwhile, a control group followed an “ad libitum” MedDiet, under which there were no caloric restrictions. They also were not offered any advice on physical activity or weight loss.
The health outcomes of the two groups were compared at the end of a six-year follow-up period and it was revealed that diabetes incidence was 31% relatively lower in the intervention group than with the control group. The intervention group also showed a mean weight reduction of 3.7% and waist circumference reduction of 3.6 centimeters.
The new results build on earlier findings by many of the same researchers, who were involved in the long-term Prevención con Dieta Mediterránea, or PREDIMED, trial in Spain, that even the higher-fat version of the MedDiet provides a 30% reduction in T2D incidence when compared with a strict low-fat diet, despite only “minimally” reducing body weight.
A second trial, dubbed PREDIMED-Plus, was launched in 2013, and the current study is a secondary analysis of that data, designed to determine whether adding caloric restriction and physical activity to the MedDiet would provide more benefits beyond those observed with the typical diet alone, according to senior author Dr. Jordi Salas-Salvado, a professor at Rovira i Virgili University in Tarragona, Spain, and principal investigator for a national scientific consortium on obesity and nutrition.
He told UPI the latest findings revealed yet more angles to the health benefits of the MedDiet.
While other studies have already demonstrated that diabetes can be prevented through a low-fat diet combined with increased physical activity, “no previous trial has assessed the effect of energy reduction in the context of a healthy, relatively high-fat diet, such as the Mediterranean diet,” Salas-Salvado said in emailed comments.
The “energy-reduced” version of the Mediterranean diet used in the new study “was defined as a traditional MedDiet with a planned reduction of 600 kilocalories per day, providing 35% to 40% of calories from fat, 40% to 45% from carbohydrates, 20% from protein and covering the vitamin and mineral recommendations established for the population to which they are addressed,” he said.
Participants “were encouraged to consume more vegetables, fruits, whole cereals, legumes, nuts and extra-virgin olive oil, while limiting meat, processed meat sugar-sweetened beverages, and other ultra-processed food, foods with added sugars, and cream.”
Study co-author Dr. Frank B. Hu, a professor and chairman of the Department of Nutrition at Harvard T.H. Chan School of Public Health, told UPI the findings provide “strong evidence to support the benefits of a Mediterranean diet combined with physical activity and modest weight loss can reduce risk of type 2 diabetes by nearly one-third over six years.
“These findings have important public health implications as we are facing global epidemics of obesity and diabetes. The Mediterranean diet is palatable and sustainable and can be adapted to different cultural settings. Adding calorie control and exercise can enhance the health benefits of the diet,” he said.
Agreeing that assessment was Dr. Elena George, a practicing dietician, nutrition researcher and senior lecturer at Deakin University in Melbourne, Australia, who was not connected with the study.
She said it “reiterates the benefits of the MedDiet for diabetes, and that the addition of even modest weight loss enhances the health benefits as seen in reduced incident diabetes.”
The diabetes prevention benefits shown in the paper would have been even “more profound” if an “actual control group” had been used, rather than comparing to interventions. Both groups improved diet quality and hence saw some benefits — the added calorie deficit and physical activity just demonstrated more pronounced benefits, she noted.
“There is no doubt improving diet quality contributes to anti-inflammatory and antioxidant effects that attenuate the cardiometabolic risk factors that lead to diabetes onset and progression,” George said. “The addition of modest weight loss and potentially improved adiposity [the condition of having excess body fat] is also beneficial.”
Holistic lifestyle interventions that address multiple factors to manage chronic diseases such as type 2 diabetes “are superior as they not only contribute to overall healthy habits as a collective, but physical activity helps maintain calorie deficits, improve body composition, and fitness, although not just frequency but type of exercise is an important consideration,” she added.
The protective benefits of a typical MedDiet come not from a low-fat strategy, but rather from its ingredients, observed Farah Naja, a professor of nutritional epidemiology and health researcher at the University of Sharjah in the United Arab Emirates.
Naja, who also was not connected to the Spanish study, told UPI the observed protective effect of the energy-reduced MedDiet on diabetes risk “could be due to the weight reduction, as demonstrated by the lower body weight and waist circumference in the intervention arm.
“It would be of interest to investigate whether a similar protective effect would be obtained from an intervention arm using same energy reduction and physical activity but not based on the MedDiet,” she said.