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 10% drop in body weight four days after receiving the jab.
Two slightly different versions of the vaccine were studied. Both produced a sustained 10% reduction in body weight after booster injections were administered after three weeks.
The slimming effect was not seen in a matched group of 10 untreated mice.
Lead researcher Dr Keith Haffer, from the US company Braasch Biotech in South Dakota, said: "This study demonstrates the possibility of treating obesity with vaccination.
"Although 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 last year in The Lancet medical journal showed that almost half of all British men could be obese within 20 years.