When a virus gets into your body, it often tries to increase your metabolism so that it can reproduce more quickly by using fatty acids to build protective envelopes.

But current anti-obesity drugs help slow the metabolism, and could thus be used to fight infections such as influenza, hepatitis and HIV, according to a new study.

Researchers from the University of Rochester Medical Center and Princeton University tried to find exactly how the metabolism turns sugars you eat into those fatty acids.

Among other things, "we also found that if you target these increases in fatty acid metabolism using existing anti-obesity and anti-metabolism drugs, you inhibit viral replication," said author Joshua Munger.

They were looking for processes they could stop that would not effect normal functioning of the body. They developed a technique that, in the lab, cut virus production 100-fold.

The work was published in the journal Nature Biotechnology.