The team started with a pair of drugs that are effective at transforming white "adipose" cells into brown ones that burn fat, rather than store it. While very effective at that chore, the drugs have adverse side effects that can limit their use. If targeted to specific parts of the body that contain fat, however, the negative consequences can be limited.

That's where the tech comes in: The drugs are stored in nanoparticles' hydrophobic cores using PLGA, a polymer commonly used in drug delivery systems and medical devices. The outer shell, meanwhile, is embedded with molecules that target proteins found uniquely in the blood vessels lining fatty adipose tissue. That turns the nanoparticles into guided missiles that seek out fat cells and release drugs to transform it.

When the system was tested in obese mice, the animals lost 10 percent of their body weight, improved cholesterol and triglyceride levels and showed a reduced risk for diabetes. One potential problem is the need to intravenously introduce the nanoparticles. "For it to be more broadly applicable for treatment of obesity, we have to come up with easier ways to administer [it]," says Omid Farokhzad from Brigham and Women's hospital. However, the team may be able to use nanoparticles that can be swallowed and absorbed through the digestive track.

The treatment has yet to be tested on humans, but could provide a new way to help obese patients, especially those at risk for diseases like diabetes. The Biggest Loser study shows that the metabolism of many folks drastically slows after successful weight loss, helping it return with a vengeance. If we can force our fat cells to work with us, rather than against us, we may be able to regain the advantage.