The researchers have created long lasting hormones which trick patients’ brains into thinking they have eaten enough food.
The approach mimics what happens when morbidly obese patients undergo gastric bypass operations to help them lose weight.
The scientists, based at Imperial College London, have just finished the first tests in patients with positive results and are now preparing to start larger trials.
They hope that using a drug will provide a safer alternative to surgery, which is currently expensive and can only be carried out in a small proportion of patients.
Professor Steve Bloom, head of the division of diabetes, endocrinology and metabolism at Imperial College, who has been leading the work, said: “Gastric bypass surgery works very well in patients.
“However, there is a world pandemic of obesity that is causing people to die from related diseases. We can’t expect to conduct surgery on half of Europe, for example.
“So we asked the question of whether we really need to carry out the surgery at all.
“If you have a problem with your gut and can’t handle too much food, the gut sends signals to the brain saying don’t eat so much.
“Gastric bypass surgery appears to fool the gut into thinking there is a problem and sends messages to the brain.” Around a quarter of all adults in the UK are now considered to be obese, leading to health problems such as heart disease, diabetes and an increased risk of cancer.
Last year there were 11,700 hospital admissions due to obesity — 11 times the figure around a decade ago.
There were also around 5,400 gastric bypass operations carried out last year on the NHS and it has been found to be highly successful at reducing the weight of patients.
The surgery attaches the small intestine to a small pouch created from the upper part of the stomach, which is then linked to the rest of the intestines.
However, often patients who undergo the surgery suffer complications and need further surgery and there have been a small number of deaths.
Initially it was thought that gastric bypass surgery worked by reducing the amount of food that can be held by the stomach.
However, patients were found to have elevated levels of satiety hormones, the chemical signals released by the gut to control digestion and hunger cravings in the brain.
Patients who had undergone surgery were also found to prefer less fatty foods, so it is thought that the hormones also change the patients’ desire to eat.
Professor Steve Bloom has now been given £2 million by the Medical Research Council to see how much weight loss can be achieved using three of these hormones.
Obese patients will wear an intravenous pump, worn around their waist, to painlessly deliver small, regular doses of the hormones GLP-1, OXM and PYY.
These hormones normally last only a few minutes in the human body so they need to be continually delivered.
However, Professor Bloom and his colleagues have also developed versions of these hormones that can last up to a week before they start breaking down.
This means patients could take a single weekly injection to control their appetite.
He has just finished a small phase 1 clinical trial in obese patients on one of the synthetic hormones and found they lost weight and experienced a long lasting reduction in appetite over a five week period.
Professor Bloom said: “The long term aim is to make new drugs that are long lasting so you can have an injection once a week without needing bypass.
“With surgery, everyone responds differently and you cannot adjust it like you can a drug. Maybe a third of patients don’t lose enough weight and some lose too much.
“With a medicine, you can change the dose quite easily and this will give much more control over how much weight people lose.”
Tam Fry, spokesman for the National Obesity Forum, said: “All impulses come from the brain so if you can tell the brain that you are full this could solve problems with overeating.
“Appetite suppressants are going to be the best way for the future. We have a history of drugs for obesity that have produced high hopes but have failed to deliver.
“So there is a real need for a satisfactory drug that will stop us eating as much as we do.”