How drug converts, burns ‘bad fat’ that holds on to calories

Scientists have long know that there’s ‘good fat’ and ‘bad fat’ in our bodies. Now United States (US) researchers team have identified a way to convert this harmful white fat that holds on to calories into beneficial brown fat that helps burn them – at least in mice.

The findings could pave the way for new treatments for obesity and diabetes. A team found that blocking the activity of a specific protein in white fat triggered the fat to turn into beige fat, a type of fat in between white and brown – which has obesity fighting powers.

The study was published in the journal Cell Reports. “Our goal is to find a way to treat or prevent obesity,” said first author Irfan Lodhi, assistant professor of medicine at Washington University School of Medicine in St Louis.

“Our research suggests that by targeting a protein in white fat, we can convert bad fat into a type of fat that fights obesity.” White fat stores calories and pads our bellies, hips and thighs. In contrast, brown fat, found near our necks and shoulders, burns calories through a process that generates heat.

Beige fat was discovered in humans in 2015. Lodhi said it functions more like brown fat than white fat and can protect against weight gain. His team discovered that blocking the protein caused the fat cells to heat up and burn calories.

The team carried out a series of experiments on mice, which had been genetically engineered to be unable to make a key protein in their white fat cells. Those mice had more beige fat and were leaner than their litter, even when they ate the same amount of food as other mice. They also burned more calories.

“Mice normally have very low levels of the protein, called PexRAP, in their brown fat,” explained Lodhi. “When we put the mice into a cold environment, levels of the protein also decreased in white fat, allowing that fat to behave more like brown fat. Cold induces brown and beige fats to burn stored energy and produce heat.”

When the researchers blocked PexRAP in the rodents, they converted white fat into beige fat that could burn calories. More than two billion adults and children globally are overweight or obese – which equates to one-third of the world’s population.