Are we making progress in childhood obesity?
It is well known that more people today are overweight or obese than in the past. This has been a steady trend for decades, but there is some recent evidence this increase has stabilized. This is promising. Since many obese adults began as obese children, during the last decade physicians who care for children have devoted considerable effort to reversing the trend. This is important because obesity sets up the individual for a host of chronic disease problems later in life. How well are we doing? Are we getting anywhere? A recent study published in the journal Pediatrics gives us some answers about that question.
The study was a survey of adolescents during three time periods: 2001-2002, 2005-2006, and 2009-2010. The survey looked at several things. These included physical activity and screen time — time spent watching TV, playing video games, etc. It assessed several dietary issues, including number of portions per day of fruits and vegetables, sweetened beverage consumption, and chocolate and other sweet intake. The survey also measured how many days each week a child ate breakfast, since skipping breakfast has been associated with weight gain.
What did the investigators find? Well, there is both encouraging and discouraging news. First, the encouraging news: they found improvement in all the measures. On average, over the time period studied, kids exercised a bit more, ate more fruits and vegetables and drank less sugary drinks, and spent a bit less time in front of the TV. These encouraging trends happened across all age and socio-economic groups.
The discouraging news is that, first, although the average of these behaviors was in the right direction, the majority of adolescents still rank poorly in all these measures that are associated with obesity. More than that, obesity, as measured by the body mass index (BMI), continued to increase over the time period, rising from 10.3% of adolescents in 2001 to 12.7% in 2009. Yet there is a glimmer of hope: the increase occurred between 2001 and 2005. There was no change between 2005 and 2009. In addition, the number of kids classified as overweight but not obese dropped just a bit. The graph from the article lays out what is really the bottom line.
This study also brings up an issue we see a lot in clinical medical research: the contrast between process measures and actual outcome measures. For example, we assume that emphasizing hand washing decreases infection rates in hospitals. So we focus on the process measure of improving hand washing rates. Unfortunately, process measures, especially of complicated, multi-factorial problems like obesity, don’t always reflect the underlying problem we are studying.
The other issue that sometimes comes up is that the process measure we think improves the situation is actually just an association, not a cause and effect thing. If that’s the case improving the process measure may not have any effect on the basic problem.
Still, I am encouraged by these results and hope they persist over time.