A widely reported government study that said obesity (search) is about to overtake smoking as the No. 1 cause of death in the United States contained statistical errors and may have overstated the problem, health officials acknowledged Tuesday.

The government is working on a rare correction to the study.

The Centers for Disease Control and Prevention (search) said in March in a study co-authored by its director, Dr. Julie Gerberding (search), that a poor diet and physical inactivity were responsible for 400,000 deaths in 2000, a 33 percent jump from 1990.

However, the CDC admitted Tuesday that it made an error in calculating how many people died from obesity in the last decade.

Although CDC officials declined to specify the corrected number of deaths, The Wall Street Journal reported that the agency may have overstated the number by 80,000, representing an increase of less than 10 percent from 1990 to 2000. The errors were first reported by the Journal on Tuesday.

The mistakes consisted of simple mathematical errors, such as including total deaths from the wrong year, the newspaper reported.

"I think there were some statistical miscalculations, but I also think there is a differing of opinions in regards to methodologies to make these calculations," CDC spokesman Tom Skinner said. "This is certainly not scientific misconduct; there's no allegation anyone had any intent to falsify data."

Skinner said the CDC plans to submit a correction to the Journal of the American Medical Association, which published the study in March. He said the correction will explain how the error was made.

The agency also has asked the Institute of Medicine, a federal scientific advisory organization, to hold a two-day workshop next month to reach a consensus on the proper way to calculate the health effects of obesity, Skinner said.

In addition, the agency is reviewing how to prevent "miscommunication" among scientists when subjecting studies to expert review before they are published.

The errors apparently were discovered soon after the CDC study was published, as scientists inside and outside the agency began to dispute its findings, publishing letters in JAMA and the journal Science. Rep. Henry Waxman, D-Calif., also asked the General Accounting Office, the auditing arm of Congress, to investigate.

That prompted the CDC to begin an internal review.

The agency originally announced that more Americans could soon be dying of obesity instead of smoking if current trends persisted. It put the number of obesity deaths at 400,000, compared with 435,000 from tobacco.

But even when the errors are corrected, Skinner said, "it's not going to change the fact that obesity is the second leading cause of preventable death."