Men who are overweight or obese when diagnosed with prostate cancer are twice as likely to die from the disease, according to a new study.

The study, by Dr. Jason Efstathiou from Massachusetts General Hospital, followed about 800 people for eight years to determine the results.

To be considered overweight, patients had to have a BMI greater than 25.

After five years, the prostate cancer mortality rate for men with a normal BMI was less than 7 percent, compared to about 13 percent for men above that level.

Efstathiou said it's not clear from the study if losing weight after a diagnosis would help patients survive.

Estimates say that in 2007 more than 218,000 men in the U.S. will be diagnosed with prostate cancer and more than 27,000 -- about 12 percent -- will die from the disease.

The work appears in the journal Cancer.