Scientists have been able to demonstrate that humans have the ability to convert ‘bad’ white fat into ‘good’ brown fat in the same way as animals, heralding a potential breakthrough which could have significant implications for global efforts to tackle obesity and sedentary behaviour.

White fat has been vilified as a key component in obesity as it stores energy as large fat molecules, increasing risk of obesity, diabetes and heart disease, whereas brown fat has much smaller molecules and is specialised to burn them, converting excess energy into heat. As a result, the ability to convert white fat into brown has been hailed by experts as holding ‘much promise’ in treating symptoms of obesity and sedentary lifestyles.

Previous studies have shown that brown fat is able to ‘communicate’ with the brain to provide indications of energy levels, while other research has found that when activated, brown fat can increase metabolic rate while also lowering blood glucose levels.

For the latest study, researchers from The University of Texas Medical Branch (UTMB), were able to demonstrate that white fat in humans can also turn into a form resembling brown fat, but the process requires severe and prolonged adrenaline-releasing stress.

Burn trauma has been identified as one of the rare causes of severe and prolonged stress where adrenaline-release is massively increased for several weeks following the injury. Consequently, the authors enrolled 72 patients that had sustained severe burns over approximately 50 per cent of their bodies, while 19 healthy people served as a comparison group. Samples of white fat were taken from the burned patients at various stages to measure the metabolism of the fat samples, the makeup of the fat cells and the patients' resting metabolic rates.

The researchers found in burn patients that there was a gradual shift in molecular and functional characteristics of white fat to a more brown fat phenotype over time, suggesting progressive browning of white fat occurs in response to a burn injury.

"Our study provides proof of concept that browning of white fat is possible in humans,” said lead author Labros Sidossis, UTMB professor of internal medicine.

“The next step is to identify the mechanisms underpinning this effect and then to develop drugs that mimic the burn-induced effect.”