Cathy Seipp, CNN • Updated 9th February 2020
( CNN ) — Would a 30-mile driving distance from any fast food chain result in a 15% healthier diet?
One of the two latest studies on the topic says yes — but some question how dramatic the results really are.
A new analysis, commissioned by Harvard Medical School, found that if dietary changes outside of local borders in the United States were adopted nationwide, just 15% of adult obesity would disappear. But the research does acknowledge that the estimates may be overly conservative.
“This is a small but meaningful number that has the potential to dramatically reduce the health care costs associated with obesity,” said Dr. Richard Marcus, a professor of pediatrics at Harvard Medical School and the study’s lead author.
Additionally, such a move could reduce cardiovascular disease, diabetes and some cancers, according to Marcus.
Concept to spread to other countries
In a second study, which didn’t involve Harvard, researchers from the University of Washington at the Naval Medical Center in Camp Pendleton, California, found that individuals in the study were in 15% more obese if they lived 1.5 miles from any location that sells or recommends unhealthful junk food.
“The implication is that the mere presence of junk food significantly predicts obesity — and that the closer you are to an outlet, the higher the odds of consuming these unhealthy foods,” said Robert Mann, a PhD candidate at the University of Washington and one of the study’s authors.
When the results from both studies were merged, Mann and his co-authors found that healthier diets tied to junk food were associated with fewer post-meal snacking. This behavior can lead to weight gain, in turn causing weight gain and a larger chance of obesity.
Researchers also found that adopting a healthier diet after driving 30 miles away from any establishment that recommends or sells unhealthy food was associated with 31% higher odds of eating healthy items than if traveling outside the 30-mile limit.
In a comparison to 1.5 miles, the new study found, the national change in nutrition recommendations was significantly associated with a mere 0.3% of weight loss. This issue, however, is complicated.
Compared with diets that worked well in the study, he says, those that required driving 10 to 20 miles, or longer, yielded the highest number of “excess calories.”
This finding lends some weight to previous studies that have found that people and adults in general don’t sustain weight loss by dieting alone. The findings of this study call into question whether people can “bulk up” and eat healthfully on their own.
Bottom line: Should Americans turn to their GPS and tout a healthier diet inside of their own communities?
“(Doing so) seems a lot more reasonable than making assumptions about how every corner coffee shop is going to change the world,” said Darren Seifer, deputy food and nutrition editor at the New York Times. “This is just one paper. If they find that people in the city actually are better off with this type of policy, they can definitely take it and make it work for them. But it’s going to take some time.”
Some skeptics say that if the answer to this question is “yes,” then why stop there?
They recommend keeping more than one ZIP code across the United States under a healthy diet regime and look to cities like Oakland and New York City for inspiration.
According to the U.S. Food and Drug Administration, New York City’s calorie disclosure laws are associated with an 18% reduction in junk food consumption. In addition, the City of Oakland expanded nutrition and calorie labeling laws for restaurants, cafeterias and vending machines, and mandated that food vendor carts provide calorie and nutritional information. In the State of California, it is illegal to give out nonnutritious food to children under 12.
Other cities that have taken bold steps to curb obesity include San Francisco, Berkeley, Denver, Minneapolis and Lawrence, Massachusetts.