"Brown fat" injections could solve the obesity problem

Most fat cells are called white fat cells - they store excess energy and make it tough to lose weight. But we've discovered how to turn mice's white fat cells into energy burning brown fat cells, and humans could be next.

Weight loss isn't just about shifting mass - it's about finding ways to burn more energy through activity than we consume from eating. Those activities can (and should) include exercise and other physical exertion on a macro scale, but our individual cells are also capable of pitching in on the fight against weight gain. Brown fat cells are particularly good at this, as they naturally burn off excess energy instead of storing it.

Now researchers have found a way to turn energy storing white fat cells into energy burning brown fat cells. Yu-Hua Tseng, a researcher at the Joslin Diabetes Center, found that mice fat tissues and skeletal muscles would, when exposed to the protein BMP-7, start displaying all the signs of brown fat cells. When the researchers added the diabetes drug rosiglitazone to the mix, even more brown fat started to emerge from the white fat cell cultures. They were also able to take these new brown fat cultures and inject them back into the adult mice. The cells survived and developed into mature brown fat cells, another excellent sign that it's possible to change one fat cell into another.

There is a snag, however. The treatment relied on finding particular fat cells that were naturally marked with the protein Sca1. That protein is unique to mice, and we don't know what its human equivalent is, which makes directly translating these results tricky. Still, BMP-7 did seem to have some moderate effects on tests on human fat cells cultures, so there's hope that this can be worked into a similar transformational treatment.

Tseng explains what this result could mean for people struggling with obesity:

"Given that obesity is a major risk factor for type 2 diabetes, cardiovascular disease and other metabolic disease, finding new ways to reduce body weight is really essential. Of course, diet and exercise are still the best approaches for losing weight in the general population, but for people who are genetically predisposed to obesity, or those who already develop detrimental metabolic disorders due to excess body weight, there is an urgent need to develop new interventions for effective and safe weight reduction. These results appear to take a significant step toward using brown fat cells in such therapies."