CHICAGO (AP) _ Obesity is not as dangerous for elderly people as it is for the middle-aged or young adults, according to a new study.

The findings are similar to those of a study reported last year that indicated being overweight shortens life expectancy up to age 75, but does not make much of a difference afterwards unless people are extremely obese.

``The absolute risk of dying gets higher and higher as you get older until you die, but the importance of obesity as a risk factor decreases,'' said Ralf Bender, an obesity researcher at the University of Bielefeld in Germany and principal author of the study published in Wednesday's Journal of the American Medical Association.

But researchers not affiliated with the study said the findings are not that meaningful.

``Obesity is a major public health problem at any age, and this study does nothing to suggest that that has changed,'' said Dr. JoAnn Manson, an endocrinologist at Harvard Medical School.

In the latest study, researchers studied 6,193 obese men and women who ranged in age from 18 to 74, following them for an average of 14.8 years. The patients, who were referred to an obesity clinic between 1961 and 1994, were grouped by their age and body mass index.

Body mass index, or BMI, is increasingly becoming the standard way of talking about obesity, since it is an easy way to compare the girth of people of different heights. BMI is body fat in kilograms divided by height in meters squared.

According to dietary guidelines issued by the Department of Agriculture, a BMI of 25 to 29.9 is considered overweight and 30 and above is obese.

Researchers found that the mortality risk for a really obese person _ with a BMI of 40 or more _ was highest for those age 30 or younger. Moderately obese men and women _ with a BMI between 32 and 40 _ who were age 50 or older had the lowest mortality risk, the study says.

Some researchers not involved with the study argued that BMI is a limited measure of obesity in the elderly because bone density declines with age. They also noted that the study participants were recruited rather than randomly selected.