The Burbs Weigh In.

Karen Gatt has lived the new suburban nightmare. Four years ago she and her husband moved from Melbourne to raise their family in a house on the Burnside Housing Estate, a half-hour drive from the city. Their new home was surrounded by grassy parks and well-cared-for walking paths-- ideal places to get the vigorous exercise a healthy body needs. The only problem was, Gatt, now 31, spent much of her time watching television and wound up going everywhere in her car. In a few years her weight had ballooned from 118 to 136 kilograms, and she developed high blood pressure and severe depression. "Last thing I did before leaving the house was I spat at myself in the mirror and watched it run down over my reflection," says Gatt. "I hated myself."

Fleeing the crowded, polluted city to the bucolic suburbs was supposed to be good for your health. New research is showing that's not necessarily true. According to studies from the United States to Belgium, a major factor contributing to the worldwide obesity epidemic is a lack of natural exercise--i.e., walking--which has been exacerbated as populations spread out from city centers. Suburbs, it seems, can make you swell.

Call it the sprawl effect. A strip mall here, a housing development there, an industrial park yonder, all connected by roads, leave little room for pedestrians. In the September issue of the American Journal of Health Promotion, Reid Ewing, a researcher at the University of Maryland, surveyed 448 counties in the United States and found that rates of hypertension and obesity were proportional to the "sprawl index"--a measurement that takes into account population density, number of highways and distances between homes and businesses. In Burnside, for instance, wide suburban houses are built on cul-de-sacs, and the absence of local shops rules out what experts call "purposeful walking." "Movement has been engineered out of our lives," says Ewing.

At the same time, heightened fears about safety have led many parents to keep their kids from playing in the streets, ...