Slimming drug curbs the pangs of hunger

Scientists have developed a slimming drug that successfully suppresses appetite and results in a dramatic loss of weight without any apparent ill-effects.

Scientists have developed a slimming drug that successfully suppresses appetite and results in a dramatic loss of weight without any apparent ill-effects.

The drug interferes with appetite control and prevents the build-up of fatty tissue. Laboratory mice given the drug lost up to a third of their total bodyweight. Within 20 minutes of being given the drug, called C75, the mice lost interest in eating and survived apparently content on just 10 per cent of the food they normally ate.

More importantly, the drug appears to prevent a serious decline in metabolic rate - causing tiredness and lethargy - which is typically associated with living on a starvation diet. As a result, mice taking the drug lost 45 per cent more weight than mice fed the same amount of food. They compensated for the lack of food by becoming more sluggish.

The scientists, from JohnsHopkins University in Baltimore, said that C75 is likely to produce a similar effect on humans because appetite control in the brain is thought to be based largely on the same chemical pathways as those that exist in mice.

Francis Kuhajda, a pathologist and senior team member said: "We are not claiming to have found the fabled weight-loss drug. What we have found, using C75, is a major pathway in the brain that the body uses naturally in regulating appetite, at least in mice.

"We badly need effective drugs for weight loss. Obesity is a huge problem. We're hoping to explore the possibilities of this new pathway."

Discovering a biochemical pathway in the brain that controls appetite raises new prospects for developing practical slimming aids. Research into leptin, a hormone produced in fatty tissue for controlling fat deposits, has, so far, failed to produce the expected slimming drug breakthrough.

The latest study, which is published today in the journal Science, showed that even moderate doses of C75 produced a significant loss of appetite, which returned to normal after a few days. Human studies of C75 are being planned but further animal studies will be needed before they can begin.

The scientists believe that C75, which they produced synthetically in the laboratory, binds to an enzyme called fatty acid synthase, which is involved in storing excess food intake as fat. Inhibiting the enzyme caused a build-up of a chemical in the liver which acts as a precursor to fat deposition. This is thought to have an indirect effect on the brain, causing appetite suppression.

Normally when animals fast, a hormone called neuropeptide Y increases sharply in the appetite-control centres of the brain, stimulating the desire for food. However, when animals are given C75, levels of this hormone fall, leading to a loss of interest in food.

Dr Kuhajda said discovering that C75 has no effect on metabolic rate is one of the most significant findings of the study. He said: "If you try to lose weight by starving, your metabolism slows down after a few days. It's a survival mechanism that sabotages many diets. We see this in fasting mice. Yet metabolic rate in the C75-treated mice doesn't slow at all."

An accompanying article in Science said the research will lead to an avalanche of interest. It said: "Any drug that could safely and effectively block appetite and lead to weight loss could be a big money-spinner."