New drug tricks the body into burning off fat

French scientists have found a drug they say tricks the body into burning off fat - and it even works on a high-fat diet.

Reducing calorie consumption by about 20% has been shown to slow down the aging process, improve endurance and protect against diet-induced obesity and metabolic diseases such as diabetes.

Last year researchers demonstrated that these metabolic benefits can also occur with large doses of resveratrol, a substance naturally occurring in red wine.

The scientists from the University of Louis Pasteur say the drug SRT1720 which is a chemical cousin of resveratrol, protected mice against weight gain and insulin resistance. SRT1720 targets the protein SIRT1, which is thought to combat ageing.

The French team's interest in the SIRT1 protein was prompted by earlier studies showing resveratrol countered some effects of a high-calorie diet through SIRT1. The study which was led by Professor Johan Auwerxand focused on creating a potent drug that would specifically target SIRT1 and came up with the drug SRT1720.

When they experimented with mice they found that a low dose of SRT1720 partially protected mice fed a high-fat diet, from gaining weight over a 15 week period of treatment - the drug worked by shifting the metabolism to a fat-burning mode that normally takes over only when energy levels are low and at higher doses, the drug completely prevented weight gain.

SRT1720 also improved the mice's blood sugar tolerance and insulin sensitivity, which are important for warding off diabetes.

The mice on a high-fat diet treated with the higher drug dose did not become obese, and their triglyceride, cholesterol, fasting blood glucose and insulin levels were all reduced, they were also able to run approximately twice the distance as control animals in an endurance exercise test.

While the mice showed no sign of side effects, the scientists say further studies are needed to test the drug's safety and efficacy before it could be used in humans.

Dr. Auwerx says unlike resveratrol, these new chemical entities target only the SIRT1 pathway, making them more selective and potent for achieving these metabolic benefits.

Experts researching obesity say the research is interesting though it is in the early stages and is welcome as an additional route of combating the obesity epidemic and related disease.

They say any anti-obesity drug should be used alongside dietary and lifestyle changes aimed at tackling obesity - the removal of the anti-obesity drug Acomplia, from the market amid safety concerns, means there are fewer drug options available.

The new drug was developed by Sirtris Pharmaceuticals, a 'biotech' start-up acquired by GlaxoSmithKline in April 2008.

The study appears in the current issue of the journal Cell Metabolism.