Rats genetically modified to be obese lost up to 19 percent of their total weight, while rats with a normal weight lost 12 to 20 percent of their weight following short-term administration of the drug vigabatrin, they said.
The study appeared Wednesday on the website of the journal Synapse.
"Our results appear to demonstrate that vigabatrin induced satiety in these animals," said Amy DeMarco, who led the study, working in US Department of Energy's Brookhaven National Laboratory.
Brookhaven scientist Stephen Dewey had previously identified vigabatrin as a potential addiction treatment, and his research revealed a close link between addiction and obesity, including similar changes in the brain of obese people and drug addicts.
Based on that observation, researchers hypothesized that vigabatrin would sate the uncontrollable urge to eat among the obese lab rats.
"Given the growing obesity epidemic, we felt that examining vigabatrin's therapeutic efficacy for obesity was particularly relevant," said DeMarco.
Fifty adolescent and adult lab rats, both genetically bred "fat" and normal-weight, were assigned to either a control group or groups that received the drug at various levels.
The control-group rats received daily salt water injections, while the rats being studied received up to 300 milligrams of vigabatrin a day.
After 40 days, the rats receiving vigabatrin had lost an average of 19 percent of their initial weight, while the non-obese animals lost between 12 and 20 percent of their weight.
"The fact that these results occurred in genetically obese animals offers hope that this drug could potentially treat severe obesity," said Dewey.
Vigabatrin is currently undergoing clinical trials for use as a treatment against cocaine and methamphetamine addiction, researchers said.