Obesity is a multidimensional problem with many social and medical factors, but maintaining body weight essentially is a result of energy consumed and energy expended. Sheldon H. Jacobson, from the University of Illinois (Illinois, USA), and colleagues investigated he association between average adult body mass index (BMI), automobile travel (as a proxy for physical activity), and caloric intake in the US in order to predict future trends of adult obesity. The team used publicly available data on national average BMI, caloric intake and driving habits. To capture the complexity in the relationship among the three variables, they developed a multivariable model showing how calories consumed and miles driven correlate with BMI. They found that if all adults in the United States drove 1 mile less per day, the model predicted an associated decrease in the national average BMI by 0.21 kg/m2 after six years. (The national average BMI in 2010, the most recent data available, was 27.55.) In comparison, reducing diet by 100 calories per day would be associated with reducing national average BMI by 0.16 kg/m2 after three years. Even a modest decrease in BMI, like that predicted by the model, could represent significant cost savings. Observing that if drivers nationwide traveled 1 mile less by car each day, not only would fuel consumption fall, but annual health care costs could drop by billions of dollars as fewer people would be classified as obese or overweight, the study authors conclude that: “Making small changes in travel or diet choices may lead to comparable obesity interventions, implying that travel-based interventions may be as effective as dietary interventions.”
