News that life expectancy among some American women has fallen earned startled headlines, as well it should. In this country, life expectancy is something that's supposed to go up. It took a big scourge, such as the Spanish flu epidemic of 1918, to depress it.

But a study published in the online journal PLoS finds that in about 1,000 U.S. counties, women's life expectancies are shorter than they were in the early 1980s. During this time, no deadly virus rampaged through the female population. And the bristling arsenal of new medical treatments continued to grow.

The chief cause was something for which there is no vaccine: obesity, smoking and other forms of self-abuse. The victim and victimizer are one and the same &

or so it appeared to me.

The counties listed are mostly in Appalachia, the South, Texas and the lower Midwest, say researchers at the University of Washington and the Harvard School of Public Health. And although the shorter lives weren't limited to one race or ethnic background (94 percent white Washington County, in Maine, was on the list), the places affected tended to have higher proportions of African Americans.

Poor health habits are hurting babies, as well. Shocked officials at the Mississippi Department of Health report that their infant mortality rate &

which had been dragged down to 9.7 deaths per 1,000 live births by 2004 &

soared to 11.4 deaths a year later. This sounds counterintuitive, but fetuses growing in grossly overweight mothers are often undernourished. Obesity can bring on hypertension and diabetes, which starve the baby of nutrients.

As one who pays attention to diet and exercise, I have a hard time understanding what seems to be a lack of self-preservation. This is not a matter of putting on an extra 20 pounds or laying off the third beer.

This is about women getting so fat that their babies die at birth.

Am I missing something here, and is that thing compassion?

I asked David Schlundt, a health psychologist at Vanderbilt University, why many people don't lift a finger to care for themselves. His answer is complicated.

"It's not a lack of self-preservation," Schlundt said. "Most of the people are intensely unhappy about their weight. Part of the problem is the toxic environment we live in."

We're now surrounded by a tremendous amount of food, and the cheapest options &

the dollar menu or calorie-dense snacks &

are the most fattening. For women especially, food may be a way to cope with stress. (I've been there.) And for everyone, the dramatic drop in physical activity lets the pounds easily pile on.

Schlundt also points to genetic factors. While obesity contributes to the epidemic of type-2 diabetes, some populations are genetically vulnerable to it. The Pima Indians in Phoenix have the highest known prevalence of diabetes in the world. One theory is that having evolved in a desert environment over centuries, the Pima developed "thrifty" genes: They can keep going on less food. When the Pima moved to the modern city and started eating the chips and double-burgers, they quickly gained weight.

As for not adopting healthier habits, it's not necessarily a case of laziness, said Schlundt, who bikes 17 miles to his office in Nashville. Some people just aren't organized enough to take care of themselves.

"Those who develop very good self-management skills in life are economically and health-behavior-wise better able to manage their affairs," he said.

I still can't entirely buy the notion that anyone is entirely helpless against a hostile environment for healthy living, but I'll grant this: There are two Americas for health as well as wealth, and they seem further apart all the time.

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