A study by the University Hospital of Tübingen, the German Center for Diabetes Research (Deutsches Zentrum fuer Diabetesforschung, DZD), and Helmholtz Munich offers intriguing new insights into the origins of type 2 diabetes and obesity, as well as the brain's function as a critical control centre.
Unhealthy body fat distribution and chronic weight gain are linked to the brain's sensitivity to insulin. But what specific functions does insulin perform in the brain, and how does it affect individuals of normal weight? In their study, Prof Dr Stephanie Kullmann and her colleagues at the Tübingen University Hospital for Diabetology, Endocrinology, and Nephrology found the answer to this query: "Our findings demonstrate for the first time that even a brief consumption of highly processed, unhealthy foods (such as chocolate bars and potato chips) causes a significant alteration in the brain of healthy individuals, which may be the initial cause of obesity and type 2 diabetes.”
In a healthy state, insulin has an appetite-suppressing effect in the brain. However, in people with obesity in particular, insulin no longer regulates eating behaviour properly, resulting in insulin resistance.
In the study, 29 male volunteers of average weight were split into two groups. For five days in a row, the first group had to supplement their regular diet with 1500 kcal from highly processed, high-calorie snacks. The extra calories were not consumed by the control group. Both groups underwent two separate examinations following an initial evaluation. One examination was conducted immediately following the five-day period, and another was conducted seven days after the first group had resumed their regular diet.
The researchers used magnetic resonance imaging (MRI) to look at the liver's fat content and the brain's insulin sensitivity. Not only did the fat content of the liver of the first group increase significantly after five days of increased calorie intake. Surprisingly, the significantly lower insulin sensitivity in the brain compared to the control group also persisted one week after returning to a normal diet. This effect had previously only been observed in obese people.
“Interestingly, in our healthy study participants, the brain shows a similar decrease in sensitivity to insulin after a short-term high calorie intake as in people with obesity,” added Kullmann. “This effect can even be observed one week after returning to a balanced diet.”
Prof. Dr. Andreas Birkenfeld, Medical Director of Internal Medicine IV, Director of the IDM and DZD Board Member, and the study's final author, concluded: "We assume that the brain's insulin response adapts to short-term changes in diet before any weight gain occurs and thus promotes the development of obesity and other secondary diseases." He urges more research on how the brain contributes to the development of obesity and other metabolic illnesses in light of the current findings.
The findings were reported in the paper, ‘A short-term, high-caloric diet has prolonged effects on brain insulin action in men’, published in Nature Metabolism. To access this paper, please click here
Comments