Obese monkeys saw their waistlines shrink in just weeks after scientists gave them an experimental drug that zaps fat cells, a study out today said, giving hope that such a pill for humans could be on the horizon.

A research team led by scientists at the University of Texas MD Anderson Cancer Center tested a group of overweight rhesus monkeys with a drug that selectively destroys the blood supply of fat tissue.

After just four weeks, the primates lost on average 11 percent of their body weight and the researchers measured drops in body mass index (BMI) and waistline, according to the study published in the journal Science Translational Medicine.

The drug, known as Adipotide, attacks the blood supply of white adipose tissue, the unhealthy type of fat that accumulates under the skin and around the belly.

In the study, the drug achieved weight loss without the toxic side-effects as other treatments that aim to suppress appetite or increase metabolism, the researchers said.

The scientists observed that it had some damaging effects on the kidneys, which, they said, could be lessened by administering the drug in smaller doses.

"Development of this compound for human use would provide a non-surgical way to actually reduce accumulated white fat, in contrast to current weight-loss drugs that attempt to control appetite or prevent absorption of dietary fat," said co-senior author Renata Pasqualini.

And the drug could have benefits beyond the obvious cosmetic ones.

"Obesity is a major risk factor for developing cancer, roughly the equivalent of tobacco use, and both are potentially reversible" said another author Wadih Arap. "Obese cancer patients do worse in surgery, with radiation or on chemotherapy - worse by any measure."

The monkeys in the study were "spontaneously" obese, the researchers said, meaning that they were not artificially fattened but freely over-ate and avoided exercise.

The researchers plan to perform clinical trials of the drug on obese men with prostate cancer.

"The question is, will their prostate cancer become better if we can reduce their body weight and the associated health risks?" Mr Arap said.

Click here to read more.