BAKERSFIELD, Calif. -- The weight-loss drug Meridia acts on brain chemicals to help suppress appetite.

Studies have shown that obese patients taking Meridia lose more weight -- around 10 to 14 pounds -- than those taking a placebo, who only lose about 4 pounds.

But how well Meridia works for you may depend on your DNA.

A new study from researchers at the Mayo Clinic has found that people with a favorable genetic profile lost the most weight while taking Meridia.

Doctors compared two doses of Meridia to a placebo in 181 obese patients. What they found was an interaction between the medication and the patients' genes.

Those with favorable genes lost the most weight, around 10 to 12 pounds over the 3-month study.

Researchers said the genes help regulate the brain chemicals that control appetite -- the same chemicals that are targeted by Meridia -- allowing the drug and the DNA to work together to increase weight loss.