Relation to teeth brushing and weight loss
...there is no clear evidence that schools are contributing to the growth in obesity. The obesity-related complaints about school lunches, vending machines, and physical education are based largely on the assumption that these factors are causing our kids to get fat. Yet, I find little evidence to support this claim. For example, in looking at survey data on the health behavior of middle and high school students, the factor I found that best predicted whether or not a kid was obese was tooth brushing [emphasis added]. More important than how much junk food they ate, soda they drank, or physical education they received was whether or not they brushed their teeth. Among fourteen- to seventeen-year-olds, only 16 percent of kids who brushed their teeth more than once a day were overweight compared to 24 percent who brushed less than once a day. Of course, other factors were important as well -- teenagers who play more computer games, eat more fast-food, and drink less whole milk were also more likely to be obese -- but these factors were tiny in comparison with tooth brushing. Meanwhile school policies, such as whether the kid was in physical education or ate school lunches, had no predictive power for whether or not a child was obese.Now obviously the act of brushing one's teeth plays little direct role in a child's weight, but it is a good indicator of something else -- in what type of household the child lives. Children who brush their teeth more often are more likely to come from homes where health and hygiene are a priority...In other words, outside of genetics, the biggest factor predicting a child's weight is what type of parenting they receive [emphasis added].
That is from J. Eric Oliver's Fat Politics: The Real Story Behind America's Obesity Epidemic. Here is my previous post on the book; the comments are open. via Marginal Revolution