Already blamed for traffic jams, habitat destruction, and the loss of community character, sprawl is now being linked to another ill: flab.
The suburban landscape forces people to drive everywhere and virtually rules out the opportunity to walk and be active on a regular basis, according to Dr. William H. Dietz, director of the Division of Nutrition and Physical Activity at the Centers for Disease Control in Atlanta.

''This is something where we need more data, but my personal belief is that community structure is tightly linked to physical activity,'' said Dietz, 56, who left Newton and a respected position at the New England Medical Center for the CDC to pursue a crusade against obesity.  He is now one of a handful of researchers in the nation studying the ways that development patterns influence personal habits - fortifying claims by environmentalists that sprawl is a health hazard.  ''I would not go so far as to say that suburban sprawl makes us couch potatoes - that's a thesis, not a fact. But it's a promising avenue to explore,'' Dietz said.  A project dubbed ''Smart Track'' is looking at how neighborhood design, car use, and physical activity relate to each other, using a sample of 400-500 people in Atlanta.

''It was quite a shift for me to move to Atlanta and learn that there was no place for me to walk to shop, and that when I went out to a restaurant I had to drive to a shopping center,'' Dietz said. ''Post offices and dry cleaners are all in shopping centers. You drive there even if it's a mile away. Traffic is bad and it's difficult to walk anywhere.''

In Newton, he said, ''our children walked to school, from Newton Centre. What made that possible was sidewalks and crossing guards and neighborhood schools. I could walk into Newton Centre to do errands.

''Newton and Boston are walkable communities with central shopping areas.''
Citing US Department of Transportation statistics, Dietz said that 25 percent of all trips are less than a mile, but that 75 percent of those trips are made by car.

In addition, long commutes eat up the time that people have for preparing healthy meals, spending time with their children, and going to the gym.
Physical activity plays a crucial role in the development and persistence of obesity and its complications, doctors say. Sedentary lifestyles have been linked to heart disease, diabetes, osteoporosis, and some cancers.
Medical researchers estimate that nearly one in four Americans is obese and 60 percent of Americans are overweight.

Even walking a small amount each dayhelps, according to Dietz and two CDC colleagues, health scientists Richard Killingsworth and Jean Lamming, leaders of the Active Community Environment Initiative.

Some of that initiative's recommendations include designing neighborhoods so people have the opportunity to walk, with more sidewalks, established and safe pedestrian routes to schools, and parks and recreational facilities in walking distance to lure children away from sitting in front of the television.
For his part, Dietz said more data is needed to inform the ''role of community infrastructure in physical activity levels. But this does bring us into the conversation with people who want to reduce reliance on cars and create liveable communities.''

Studying child obesity all his professional life, Dietz didn't plan on becoming an expert on land use and development.  But he said the physical landscape is a major factor in America's bulging waistlines, for the young and old.
''I came here to broaden my capacity to understand this problem and do something about it,'' he said.  His goal, he said, remains the same: ''To make physical activity part of everyone's life.''

This story ran on page B2 of the Boston Globe on 10/8/2001.
copyright Copyright 2001 Globe Newspaper Company.