According to a new study, obesity may develop as a result of chronically high insulin levels, not the other way around. This was an experiment done with mice, showing that animals with persistently lower insulin stay trim even as they indulge themselves on as much fatty foods as they like. The researchers say that this study is the first of its kind to directly show that circulating insulin itself drives obesity in mammals.
For the study, mice were chosen because they have a beneficial genetic quirk: two insulin genes. Primarily, insulin1 resides in the pancreas of mice, whereas insulin 2 shows up in the brain, as well as the pancreas. The researchers eliminate the insulin2 altogether and varied the number of good copies of insulin1, in order to produce mice that varied only in their fasting blood insulin levels. Therefore, the mice with one copy and lower fasting insulin were then completely protects from obesity when they were presented with high-fat food. This came with no loss of appetite, as well as the added benefits of lower levels of inflammation and less fat in their livers, too.
The scientists traced the difference to the fact that the fat tissue had been ‘reprogrammed’ to burn and waste more energy in the form of heat. The white fat that mice have now looked and acted in a similar way to the coveted, calorie-burning brown fat that is most familiar for keeping babies warm.
James Johnson, of the University of British Columbia, praises the results as in-keeping with other clinical studies that have showed diabetics use more insulin on a long-term basis with weight gain. He explained, ‘We are very inclined to think of insulin as either good or bad, but it’s neither’. However, Johnson warned that ‘This doesn’t mean anyone should stop taking insulin; there are nuances and ranges at which insulin levels are optimal.’
However, Johnson is yet to determine what the results might mean in the clinic, especially seeing as drugs designed to block insulin have been shown to come with unwanted side effects. Yet, according to Johnson, ‘there are ways to eat and diets that keep insulin levels lower or that allow insulin levels to return to a healthy baseline each day.’