More exercise, less eating and no smoking or drinking.

While all are considered hallmarks of good health, a new study suggests that none do much to trim the death rate of America's poor.The poor have a death rate as much as three times higher than that of others. According to a study published in Thursday's Journal of the American Medical Association, smoking, drinking alcohol, overeating and lack of exercise cause no more than 13 percent of the gap.

"For a long time, we've been focusing on trying to reduce risky health behaviors, such as smoking, drinking and being physically inactive," said Paula Lantz, the study's author and a professor of public health at the University of Michigan. "That's an important goal, but it won't fully close the gap between poor people and other people."

More important causes, experts say, may include lack of medical care, the stress of being poor, dangerous jobs and polluted homes and neighborhoods.

Beginning in 1986, the 7 1/2-year survey looked at 3,617 Americans and their living habits. It took into account all kinds of deaths, from cancer to gun battles with the police. The biggest killers were heart disease and cancer.

Dr. Redford Williams, chief of behavioral medicine at Duke University, said in an accompanying editorial that the research is convincing.

"These findings indicate the need to broaden the search" for the real causes behind the higher death rate, he said. He pointed, for example, to "the harsh and adverse environment in which poorer people live."

Bruce Link, an associate professor of public health at Columbia University, agreed: "People with more resources, more knowledge, more money, better access to health care, tend to capitalize on that."

The study said government reports and newspaper opinion-page pieces assume smoking, drinking, overeating and lack of exercise are to blame for high death rates among the poor. The survey did find that poor Americans tend to smoke and overeat more and be less active, though they were not the heaviest drinkers.