An obesity vaccine has been developed that uses the immune system to keep the body slim.
The "flab jab" has shown promising early results in mouse studies.
If the vaccine passes further safety trials, scientists believe it could provide a revolutionary new weapon against obesity.
Currently the only non-dieting options for controlling weight are surgery and strong drugs that can have serious side effects.
The vaccine works by stimulating the immune system to attack a hormone that promotes slow metabolism and weight gain. In tests, obese mice fed a high fat diet saw a 10pc drop in body weight four days after receiving the jab.
Two slightly different versions of the vaccine were studied. Both produced a sustained 10pc reduction in body weight after booster injections were administered after three weeks.
Lead researcher Dr Keith Haffer, from the US company Braasch Biotech in South Dakota, said: "Though further studies are necessary to discover the long-term implications of these vaccines, treatment of human obesity with vaccination could provide physicians with a drug and surgical-free option against the weight epidemic."
Research published in Britain last year in 'The Lancet' showed that almost half of all British men could be obese within 20 years. By 2030, four in 10 British women could be at obese weight levels, the research shows.
Being obese is defined as having a Body Mass Index (BMI) -- a measurement relating height and weight -- of 30 or more.
Up to 30,000 Britons die prematurely every year from obesity-related conditions.
The new vaccine uses a modified form of somatostatin, a peptide protein molecule that functions as a hormone.
In both mice and humans somatostatin suppresses growth hormones that boost metabolism and cause weight loss.
In mice, the vaccine reduced body weight without affecting normal levels of growth hormones.
Although the mice received large amounts of the vaccine, a recent unpublished study in pigs suggested it was effective at much lower doses.
Further research will look at the vaccine's effects in obese pigs and dogs before moving on to human trials.