A drug that’s been around for 50 years could become the new weapon in a fight faced by millions of Australians: obesity.

Twelve million Australians are overweight or obese, so it’s no wonder experts are looking at new ways to beat the major health issue.

Antabuse, a medicine used for alcohol dependence, has proved so powerful for weight loss, University of Sydney scientists couldn’t believe their eyes – but there’s a catch.

US researchers first began to test the drug on mice to combat obesity because of its anti-inflammatory effects on the liver.

Middle-aged mice were fed high-fat diets before being given Antabuse, with a group tested using a high dose of the medicine disulfiram losing as much as 40 per cent of their body weight in just four weeks while also protecting the animals’ livers and pancreases.

The weight loss was an effect of Antabuse that the researchers were previously unaware of, Professor Stephen Simpson, from the University of Sydney’s Charles Perkins Centre, said.

“They’re losing more calories per amount eaten, than the control animals,” Prof. Simpson told 9News.

Along with the research team, Prof. Simpson – co-author of the book How To Eat Like The Animals For Good Health, focusing on the science of healthy eating and appetite – has advised against humans using the drug to lose weight unless it’s part of a clinical trial, because the current findings only relate to mice.

Any future approved prescriptions of the drug specifically for weight loss would also require a person to stop drinking alcohol.

Despite that, Prof. Simpson believes there are other therapies that could also help a person lose unwanted kilograms.

“A simple thing to do is to take out ultra-processed food from your diet,” he said.