And it's been well documented that people who don't know if they'll be able to buy food for their families at the end of the month go for calories per dollar.
People are also eating out much more than they were previously, and portion size is more difficult to control when you eat out. Also people are not sitting down to eat at regularly scheduled meals and instead tend to graze during the day. And, for people who are prone to gain weight easily, that kind of grazing ends up providing more calories.
On the "calories out" side, the amount of time devoted to video games, television or computers has become very prevalent during these last few decades. In inner cities, where the concentration of overweight kids appears to be the highest, there is fear of letting kids play outside because their neighborhoods are not safe. Children in all neighborhoods are also less likely to walk to school. And the rates of participation in organized sports are really remarkably low among kids.
How is obesity in children defined?
For adults, a body-mass-index (BMI)—which is measure of body weight in relation to height—over 25 is overweight and a BMI of over 30 is obese. There aren't single numbers like that for children. In fact, the Centers for Disease Control avoid the term "obesity" in childhood because the value that is abnormal continues to fluctuate as children grow and change with puberty. Instead, being between the 85th and 95th percentile BMI for gender and age is considered at risk for overweight. And being at the 95th percentile or above is considered overweight.
