Obese people can now have a pacemaker implanted into their stomach to help them lose weight.
The device helps control hunger
Doctors at the privately-run National Centre for Obesity in Worcestershire say "Gastropace" tricks the brain into thinking it has eaten enough.
Studies suggest the device may be better than alternative treatments, such as stomach stapling or drugs.
The operation, which is not yet available on the NHS, costs £12,500 at the National Centre for Obesity.
The matchbox-sized device is implanted into the abdomen. It is controlled by a small battery-powered unit.
The implant sends electrical signals to muscles in the stomach wall. This slows food in the intestine and makes patients feel more full.
Dr Phil Thomas, medical director at the National Centre for Obesity, said the implant helps control hunger.
"It helps patients lose weight without having to diet," he told BBC News Online.
"They just don't want to eat as much. As soon as you switch the box on, you change the way the stomach moves and this makes patients fell more full.
"Patients start to lose weight immediately."
The operation to implant Gastropace takes less than an hour.
"The surgery lasts around 45 minutes. The most a patient has to stay in hospital is one night."
A study published in Obesity Research in December suggested that Gastropace can help obese people lose weight.
Italian researchers said the device also has fewer side-effects than other treatments.
Dr Ian Campbell, chairman of the National Obesity Forum, said the procedure should be available on the NHS.
"It is a shame that this is not available on the NHS," he said.
"It does appear to be a safe and effective way of controlling weight. It is appropriate for patients who are morbidly obese and who have failed to lose weight from medical treatment.
"It may appear to be a drastic solution but the risks of being morbidly obese are very high."