July 29 (Bloomberg) -- Being fat doesn’t increase the risk of death from swine flu, according to a U.S. analysis that contradicts initial reports.

About 34 percent of the U.S. population is obese, while 38 percent of patients who died with swine flu had the condition, according to a report presented today at a vaccine conference at the U.S. Centers for Disease Control and Prevention in Atlanta. Extremely obese people make up 6 percent of the population and 7 percent of swine flu deaths.

For the seasonal flu virus that strikes every year, obesity isn’t considered a separate risk factor, and global health authorities were studying a possible link with swine flu complications from anecdotal reports by hospitals. After analyzing the available data, scientists at the CDC today said there was no unique threat for the overweight.

“Obesity should not be considered a new risk factor,” said Anthony Fiore, a CDC researcher. Obese patients may have other conditions that can complicate the flu, and doctors should still consider that when making treatment recommendations, he said.

A person is obese if their body mass index is greater than 30 or about 186 pounds for a person who is 5 feet, 6 inches tall.

About 70 percent of patients hospitalized with swine flu, also known as H1N1, have an underlying medical condition that adds to their risk for complications, Fiore said.

The analysis was prompted in part by a CDC report July 11 that 9 of 10 patients with the pandemic flu strain admitted to an intensive care unit at a hospital in Ann Arbor, Michigan, from late May to early June were obese, and seven were “extremely obese,” with a body mass index of at least 40. Three of the 10 died and seven had no other known health problems.

To contact the reporters on this story: Tom Randall in New York at trandall6@bloomberg.net

Last Updated: July 29, 2009 15:56 EDT