London: Raspberry ketones can help you lose weight and boost levels of a metabolism-regulating hormone, a report has claimed.

Raspberry ketones are fragrant compounds that occur naturally in raspberries and other fruits. The compounds can boost levels of adiponectin hormone, which regulates metabolism. Higher levels of this hormone are associated with fewer fat stores.

The ketones are normally used to give a fruity smell to cosmetics and foodstuffs but, because you only get between one and four milligrammes from every kilo of fresh fruit, a synthetic version is often used to get the same result.

And now these ketones are being sold online, in supplement form, as a slimming aid, the report said.

Millions of Americans have become convinced of powers of raspberry ketones to `melt` away fat after they were recommended by Dr Mehmet Oz, a cardiothoracic surgeon featured on The Oprah Winfrey Show.

He said raspberry ketones are `the number-one miracle in a bottle to burn your fat`.

However, Ann Ashworth, a spokeswoman for the British Dietetic Association, urges caution, pointing out that the only published research into the effects of raspberry ketones on weight loss is small studies on mice.

“Although this sounds very exciting, this evidence cannot be transferred to humans without further clinical trials,” she said.

“We need to know if it`s safe, if there are side-effects, or if it interacts with other medicines,” she added.

Consultant nutritionist Helen Bond agrees.

“People want a quick fix, especially at this time of the year, but when it comes to weight loss, no supplement can take the place of a healthy diet and exercise,” she said.

“It is not very glamorous but it will save you quite a few pennies along the way and will help you keep the weight off in the long term,” Bond said.