Scientists have found the part of the brain that makes cannabis users crave pizza, chocolate and chips.

The discovery of the part of the brain that creates the 'munchies' could help to develop pharmaceuticals for anorexia or obesity, with minimal side-effects.

Australian researcher Dr Paul Mallet of the University of New England in Armidale and team will report their rat study in the journal Neuropharmacology.

"Because smoking cannabis increases appetite, it was believed that this was somehow related to the effects of cannabis on some brain centre but that was until now not identified," says Mallet, a biological psychologist.

"We've actually identified which part of the brain is responsible for THC's [the active substance in cannabis] effect on the stimulation of appetite."

They injected THC, or tetrahydrocannabinol, into a specific region of the brain's hypothalamus, known to control feeding behaviour, called the paraventricular hypothalamic nucleus (PVN).

And they found it stimulated the laboratory animals' appetite.

"What we find is that these rats get the munchies," says Mallet.