This study investigated the relationship between green areas and body mass index (BMI) among Norwegian adolescents. It also investigated how specific variables can modify the relationship between greenspace and BMI. These variables included adolescents' use of nature, physical activity level, and mode of transportation to school.
The researchers accessed data from the Norwegian Youth Study which was conducted between 2001 and 2004, with all 10th graders invited to participate. The school-based survey used in this study collected self-reported information on adolescents' health-related issues (including weight and height), life style (including physical activity level), and living conditions (such as family situation and neighborhood characteristics). Data for the current study was based on over 10,000 completed surveys. The researchers also collected data on the percentage of green areas around schools. This involved geocoding all the schools and producing buffers with radii of 1000 meters and 5000 meters. Green areas, retrieved from land cover maps, were based on the following attributes: park, forest, open area, ocean surface, lake, river and stream, graveyard, sports arena, alpine hill, cropland, marsh, fresh water dry fall, and golf course. Areas around the schools were then rated from “least green” to “most green.”
Overall results indicated that adolescents living in the most green areas were less physically active, used passive transportation (car, bus, train) more often, and used nature more frequently. They also tended to have less healthy diets than their peers living in less green environments. Adolescents living in the greener neighborhoods were more likely to be overweight or obese than those in less green neighborhoods. These results applied to both the smaller and larger buffers, but the association was stronger in the larger buffer zone. The odds of being overweight was 1.38 times higher for adolescents living in the most green environments than those living in the least green environments. Physical activity and active transportation (walking, bike riding) decreased the odds for both overweight and obesity. No association was found between green area and use of nature.
The results of this study differ from previous studies showing a positive association between green surroundings and a healthy weight. These conflicting results could be due to differences in the assessment and measurement of green areas. Other types of assessments include remote sensing (satellite data) and proximity to parks. Different studies have also used different buffer zone areas. Differences in the prevalence of obesity from one country to another could also explain some of the differences between studies. The authors also note that Norwegian rural green areas are mostly cropland, forests, and mountains and more facilitated green areas in urban areas. It is possible that these rural green areas are less accessible or less attractive to adolescents, who may prefer more facilitated green areas. This can lead to less physical activity among adolescents in rural areas, which in turn can lead to more overweight and obesity.
The researchers call for more research on the relationship between green surroundings and the condition of being overweight or obese. They highlight the need to differentiate between green areas in urban and rural areas and to identify ways in which green areas can encourage increased physical activity among adolescents.
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