Healthy metabolism despite obesity – brown fat could be the key

29.10.2021 11:41

Not all overweight is the same and brown fat could make all the difference. A study by the research group of Florian Kiefer from the Clinical Department of Endocrinology and Metabolism of the University Clinic for Internal Medicine III of MedUni Vienna and Vienna General Hospital shows that people who are very overweight (obesity) and also have active brown fat are healthier metabolism and use more energy than people with obesity without brown fat. The new findings suggest that the presence of brown fat could protect against complications of obesity. The study has just been published in the international journal “Diabetes”.

For years, medical research has tried to understand why some people with obesity are less likely to suffer from health consequences such as diabetes or high blood pressure than others with a comparable body weight. Brown fat now seems to be identified as an important factor for the so-called “metabolically healthy overweight”. “Brown fat has long been said to have positive effects on metabolism because, in contrast to the much more common white storage fat, it can burn energy in the form of heat. Babies and small children in particular use brown fat tissue to maintain their body temperature. As they get older and are overweight, the proportion of brown fat in the body decreases,” explains Florian Kiefer.

As part of the recently published study, the Viennese research group discovered that more than a third of adults with severe obesity (BMI > 35kg/m2) still had active brown fat. The participants were first exposed to moderate cold wearing cooling vests in order to activate the brown fat, which was then detected using PET-CT.

“In adults, we find brown fat predominantly in the deep neck regions or in the chest. A short cold stimulus of around an hour is enough to activate it,” says study leader Kiefer. The overweight participants with brown fat had higher energy expenditure, less harmful abdominal fat, healthier sugar metabolism and fewer signs of fatty liver disease compared to a similarly weight control group without detectable brown fat.

Kiefer says: “It is astonishing that the participants with brown fat performed better in almost all metabolic parameters, even though they even had a slightly higher body mass index. These data show us once again that it is not just the quantity that matters, but above all the quality of the fatty tissue.”

In fact, differences in fat distribution could have contributed to the advantageous metabolic situation. In particular, deep abdominal fat (visceral fat), which represents a high risk of diabetes and heart attack, was significantly less pronounced in the group with brown fat. “It is entirely conceivable that the increased metabolic activity of brown fat causes the harmful visceral fat stores to be broken down and burned first. “Therefore, we are currently working very intensively on the development of drug therapy options to activate brown fat,” explains Kiefer.

MedUni Vienna scientists from the University Clinics for Radiology and Nuclear Medicine as well as Surgery and the Clinical Institute of Laboratory Medicine were also involved in the study. The study was supported by the Fund for Scientific Promotion (FWF), the Medical-Scientific Fund of the Mayor of Vienna and the Austrian Diabetes Society.

Service: Diabetes “Active Brown Adipose Tissue is Associated with a Healthier Metabolic Phenotype in Obesity” Herz CT, Kiefer F. et al. Link: https://doi.org/10.2337/db21-0475.