Extreme obesity is linked to extreme risks

WASHINGTON — When the fat get even fatter, their risk of death jumps, too, especially if they have an apple-shaped waistline.

So concludes a study of 90,000 women in the United States, the first to look closely at the alarming trend of extreme obesity, being at least 90 pounds overweight.

"People think of obesity as a single thing, but your risk can be modified within that," said lead researcher Dr. Kathleen McTigue of the University of Pittsburgh. She presented the study Saturday at a meeting of the American Heart Association.

The good news is that losing even 20 pounds or so will help, she said.

For the fattest women, "it would definitely improve your health prognosis if you can move yourself just one weight category over," McTigue said.

About 60 percent of American adults are either overweight or obese. The excess pounds increase the risk of diabetes, heart disease and other ailments.

The government equates obesity with a body mass index, or BMI, of at least 30. Someone who is 5-feet-4 would have to weigh 175 pounds to reach that threshold.

The index is calculated by dividing a person's weight in pounds by his height in inches, squared, and multiplying that total by 703.

Doctors typically warn that obesity increases the risk of death twofold, mostly from heart disease.

Recent studies suggest about 4 million Americans are extremely obese, with a BMI of at least 40. That translates into 233 pounds for that 5-feet-4 person.

Does losing a little weight help once the obesity threshold is crossed or does it takes radical slimming down to make a difference?

McTigue culled data on 90,000 women enrolled in the Women's Health Initiative Observational Study, a major project that is examining a variety of health issues.

She compared normal-weight women, who have a BMI below 25, with three categories of obesity: Class 1, a BMI of 30 to 34.9; Class 2, a BMI of 35 to 39.9; and Class 3, a BMI of 40 or higher.

Of the women studied, 3.6 percent were extremely obese, including 3.1 percent of white women and 9.6 percent of black women.

McTigue tracked the women's health over five years.

White women with Class 1 obesity had a 19 percent greater risk of death in that period than did normal-weight women. The extremely obese had double the risk of death.