Scientists have found a way to give white ‘bad’ fat some of the healthful characteristics of energy-burning brown ‘good’ fat to treat obesity and diabetes.

Researchers at the Columbia University Medical Centre (CUMC) have identified a mechanism that can give energy-storing white fat some of the beneficial characteristics of energy-burning brown fat.

The findings, based on studies of mice and of human fat tissue, could lead to obesity and type 2 diabetes treatment.

“Turning white fat into brown fat is an appealing therapeutic approach to staunching the obesity epidemic, but it has been difficult to do so in a safe and effective way,” study leader and professor of Medicine and the Russell Berrie Foundation Professor at CUMC Domenico Accili said in a press release.

White fat can be “browned” with a class of drugs called thiazolidazines (TZDs), which increase the body’s sensitivity to insulin.

Humans have two types of fat tissue: white fat, which stores excess energy in the form of triglycerides, and brown fat, which is highly efficient at dissipating stored energy as heat.

Infants have a relative abundance of brown fat, as protection against exposure to cold temperatures. In adults, however, almost all excess energy is stored as white fat.

TZDs have many adverse effects — including liver toxicity, bone loss, and, ironically, weight gain — which have limited the use of these drugs.

The researchers had previously shown in mice that when sirtuin activity increases, so does metabolic activity.

In the present study, they found that sirtuins boost metabolism by promoting the browning of white fat.

“When we sought to identify how sirtuins promote browning, we observed many similarities between the effect of sirtuins and that of TZDs,” lead author associate research scientist at CUMC said.

Sirtuins work by severing the chemical bonds between acetyl groups and proteins, a process known as deacetylation.

The study was published in the journal Cell.

(This article was published on August 3, 2012)
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