But new research points to a different danger zone, a frequently traversed space where your self-discipline can easily slip: that stretch between your residence and your workplace.
A study of New Orleans elementary school employees found that those who drove by—or even near—more fast food restaurants on their way to or from work had, on average, a higher body-mass index than their peers. BMI is a common indicator of whether a person is overweight or obese.
"In our daily lives, we are exposed to several healthy and unhealthy food choices, which has an impact on BMI," Arizona State University economist Adriana Dornelles, the study's author, said in announcing the findings. "The availability and variety of fast food restaurants along our commute create endless opportunities for a quick, cheap, and unhealthy meal."
The research, published in the online journal PLoS One, utilizes data from a health-related worksite intervention program for elementary school employees in New Orleans. The 710 participants, who worked at 22 different schools, had their height and weight recorded in the fall of 2006, and again two years later.
Dornelles mapped out the various types of food retailers located within one kilometer of each employee's home, the school where they worked, and along the most direct route between the two locations.
After taking into effect both personal demographic factors and elements of the built environment (including street connectivity and land-use density), Dornelles discovered several patterns, including one that no previous research has found: Employees whose commuter routes are more densely packed with fast food restaurants have higher BMIs than their colleagues, on average.
In contrast, Dornelles found no relationship between BMI and the presence of such restaurants within one kilometer of either the employee's home or workplace. (She notes that school employees "have limited time for lunch," and many presumably eat in the cafeteria.)
These findings suggest that simply driving around a city, past all those Golden Arches, exposes us to temptations that can have long-term health consequences. Fast food consumption, Dornelles notes, has been linked to "the population's overall higher consumption of fat, cholesterol, and carbohydrates, and therefore increased weight and obesity."
So if you're watching your weight, also watch your commuting patterns. Without realizing it, you can easily find yourself turning from Skinny Street onto Harm's Way.