The obesity pandemic is everywhere – along with it comes the diabetes pandemic. And it’s mostly down to food. But which diet can prevent as much damage as possible?
Since 1975, there has been a rapid increase in obese people. In 1975, 34 million men and 71 million women suffered from obesity, whereas in 2014, 266 million men and 375 million women were affected. This is accompanied by a rapid increase in diabetics. Men with a BMI over 35 are, on average, 40 times more likely to develop type 2 diabetes and the correlation is even higher for women, explained Prof. Bernhard Paulweber, Head of Metabolic Diseases and Medical Molecular Biology at Salzburg University Hospital, at the DGVM Congress in Salzburg.
According to estimates, there will be about 640 million diabetics worldwide in 2030. It cannot be denied that these findings have significant health implications. “This increase is strongly related to our lifestyle and diet. Until the 1960s, energy intake from carbohydrates decreased. Then, there was a reversal as well as a rapid increase in the intake of refined carbohydrates,“ said Prof. Paulweber.
Diabetes therapy has changed in recent decades. Until 1960, its focus was very much on diet. Today, with technological support and modern pharmacotherapy, the focal point is different, Paulweber said. “In the past, you had to reduce carbohydrates; that was the only way to successfully treat diabetes. Today, we see very individualized treatments. There’s a focus on the quality and fiber index of carbohydrates.”
Nonetheless, according to current international standards of medical care in diabetes, proper diet and nutritional therapy are important for successful diabetes therapy. Weight loss should also be pursued. Even “a modest weight loss (5 %) improves glycemic control and reduces the need for glucose-lowering medications [...] and promotes sustained diabetes remission through at least 2 years,” according to the recommendations of the American Diabetes Association.
In order to achieve this important weight reduction and also counteract the disease, a bunch of different diets are recommended for diabetics. These include low-carb as well as Mediterranean diets – but what are the pros and cons of each diet and which one is best suited for diabetics?
“Carbohydrates are always the focus of diabetes diets. Very little is said about proteins, on the other hand. But if you want to avoid hypoglycemia, you should go for carbohydrates that are low in protein. Proteins can raise insulin levels without raising sugar levels,” said Paulweber.
Avoiding carbohydrates, especially those that contain a lot of starch, has a positive effect on existing diabetes by simultaneously reducing sugar intake and, if desired, can also be combined with a Mediterranean diet.
A recent study looked into nutrition therapy for adults with diabetes or prediabetes and found that a low-carb diet was associated with weight loss, lower blood pressure, A1C reduction, increased HDL-C as well as lowered triglycerides. In the study, a low-carb diet was defined “as reducing carbohydrates to 26–45 % of total calories.” However, the authors also acknowledge that “a one-size-fits-all eating plan is not evident for the prevention or management of diabetes, and it is an unrealistic expectation given the broad spectrum of people affected by diabetes and prediabetes, their cultural backgrounds, personal preferences, co-occurring conditions, and socioeconomic settings in which they live.”
The Mediterranean dietary pattern is characterized by a high proportion of unsaturated fatty acids, plant- and fish-based meals as well as relatively few dairy products. In addition, the proportion of omega-3 fatty acids is significantly increased, and the proportion of concentrated sugars is rather low. “In addition to cardiovascular risk, a Mediterranean diet significantly improved diabetes risk, glycemic control and blood levels,” Paulweber said.
“In comparison, the Mediterranean diet comes out best overall,” according to Paulweber. He based this conclusion on a meta-analysis comparing different diets and their impact on obesity and diabetes. “However, the low-carb diet was found to be best for HbA1c. The Mediterranean diet followed in second place, with the Paleolithic diet close behind. A paleolithic diet is described as “the modern interpretation of the diet that humans ate during the Paleolithic or Old Stone Age era“ and consists of predominately unprocessed foods such as meats, fish, eggs, regional vegetables and fruit as well as nuts and seeds. The Mediterranean diet had the best effect on glucose levels, followed by the paleolithic and vegetarian diets. In general, all of these diets performed better compared to a control group. However, the Mediterranean diet performed best overall,” explained Paulweber.
In one of the few dietary studies with hard endpoints, the PREDIMED study enrolled over 7,400 subjects, 50 % of whom had diabetes, and compared their dietary patterns. The cohort was divided into two Mediterranean approaches – supplemented with olive oil or nuts – and a low-fat control group. However, it should be noted that a low-fat diet as defined in the study’s country Spain is not particularly low-fat compared to rest of Europe (37 % of daily calorie intake). The primary end point was the rate of major cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes). Based on the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years.
“There was a risk reduction of about 30 % in the two Mediterranean groups,” Paulweber said. “This includes other endpoints such as: an approximately 30 % reduction in new-onset type 2 diabetes, as well as a reduction in peripheral arterial disease, atrial fibrillation, breast cancer and heart failure. All of these conditions were positively affected by the Mediterranean diet,” concluded Paulweber.
However, there are still just a few relevant comparative studies of dietary patterns. It can be summarized: Regardless of the diet, certain behavioral rules should be followed and certain foods should generally be avoided – at least until advantages and disadvantages of each diet have been studied more. General advice is as follows:
Image Source: Jakub Kapusnak, unsplash
