Though affectionately referred to as "love handles," many of us would like to be rid of these stubborn regions of excess fat. In a new study, scientists describe the development of a skin patch that has the potential to "melt" them away.

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Researchers reveal how a skin patch helped to reduce 'love handles' in mice.

Researchers reveal how the novel patch delivered fat-browning drugs directly to the so-called love handles of obese mice. This not only reduced the amount of excess fat in the rodents by a fifth, but it also led to a reduction in fasting blood glucose levels.

Study co-leader Li Qiang, Ph.D. - of the Columbia University Medical Center in New York City, NY - and colleagues say that while the patch is yet to be tested in humans, the current study brings us closer to a noninvasive technique for the treatment of obesity and diabetes.

The researchers recently reported their findings in the journal ACS Nano.

The skin patch works by converting "bad" white fat into "good" brown fat. White fat, also called white adipose tissue, is a type of fat the body stores as an energy reserve. However, having too much of this fat - particularly around the abdominal region - can raise the risk of numerous health problems, including obesity, diabetes, and heart disease.

Brown fat, or brown adipose tissue, is preferable to white fat as it burns energy. With this in mind, researchers have been searching for strategies to increase brown fat in humans, with the aim of lowering the risk of obesity and its associated health conditions.

Dr. Qiang and colleagues believe that their skin patch may offer a noninvasive technique that meets this need, after it yielded promising results in obese mice.

"There are several clinically available drugs that promote browning, but all must be given as pills or injections," he expains. "This exposes the whole body to the drugs, which can lead to side effects such as stomach upset, weight gain, and bone fractures. Our skin patch appears to alleviate these complications by delivering most drugs directly to fat tissue."

Nanoparticles deliver fat-browning drugs

The centimeter-square skin patch consists of microscopic needles loaded with nanoparticles, which are around 250 nanometers in diameter. For their study, the researchers placed two skin patches on obese mice - one of each side of their abdomen.

The nanoparticles of one of these patches contained one of two drugs that are known to convert white fat into brown fat: rosiglitazone and beta-adrenergic receptor agonist (CL 316243). The other patch did not contain any drugs.

The team explains that the nanoparticles of the drug-containing patch slowly delivered the drugs directly to the rodents' fat tissue.

"The nanoparticles were designed to effectively hold the drug and then gradually collapse, releasing it into nearby tissue in a sustained way instead of spreading the drug throughout the body quickly," says study co-leader Zhen Gu, Ph.D., of the University of North Carolina at Chapel Hill and North Carolina State University in Raleigh.

The researchers replaced the rodents' skin patches every 3 days for a total of 4 weeks.

At the end of the 4 weeks, they found that the mice had experienced a 20 percent reduction in fat on the side that was treated with the drug-containing patch compared with their untreated side.

What is more, when compared with control mice, the treated mice showed a significant reduction in fasting blood glucose levels.

A 'noninvasive alternative to liposuction'?

Upon further investigation, the team found that the treated side of the mice possessed a higher number of genes associated with fat browning than the untreated side, which indicates that the reduction in fat and blood glucose levels identified in the rodents were down to an increase in brown fat.

They also tested the drug-loaded skin patch on healthy, lean mice. The patch increased their oxygen intake by around a fifth, which the team notes is a sign of better metabolic activity.

Taken together, the researchers believe that their study may pave the way for a safer fat-browning treatment for metabolic disorders, though human trials are needed.

"Many people will no doubt be excited to learn that we may be able to offer a noninvasive alternative to liposuction for reducing love handles. What's much more important is that our patch may provide a safe and effective means of treating obesity and related metabolic disorders such as diabetes."

Li Qiang, Ph.D.