In an earlier post I wrote about the complex causes of obesity. Too much food (especially junk) and too little exercise have an obvious role: too many calories taken in and too few calories expended out. ig portions, lots of sugar and fat, and bodies sitting around watching television or the computer screen all play a part in people getting to XXL. And the risk starts from the beginning. A major study in the U.S., published this year, established that a third of children who are overweight in kindergarten are obese by Grade 8. And almost every child who is obese stays that way into adulthood.
At the same time there is more to obesity than "calories in/calories out." A case in point is a recent study tying body mass index (BMI) to pollutants. That investigation suggests that exposure to second-hand smoke and roadway traffic may be linked to increased BMI in children and adolescents. The study followed 3,316 kids in southern California communities from the age of 10 to 18. Parents of the children were questioned about exposure to smoking and various other pollutants and traffic volume. Many other factors were controlled for: for example sex, initial BMI, parental education and income, and open space and parks near where the children lived.
The researchers concluded that there were significant differences between children who had no exposure to second-hand smoke and roadway pollutants and those who had.