Childhood obesity leads not just to teasing by peers, but eventually also to a variety of serious medical problems, ranging from back pain to heart disease and diabetes. That is why medical experts are quite concerned that obesity in children has increased markedly since the 1950s, to the point of being considered a genuine health “epidemic” (Ogden, et al., 2002). Recent projections suggest that fully one-third of all children born in 2000 will eventually develop diabetes as a side- effect of being overweight (Narayan, et al., 2003).
Why have these changes happened? One factor is probably the vast increase in individuals’ consumption of sugar especially “disguised” forms like corn syrup (Bawa, 2005). Another is a more sedentary, “stay-inside” lifestyle than in the past. The latter has happened, among other reasons, because of population shifts: cities and towns have increased in population and size, while rural areas have decreased in population, causing more people to rely on car travel more than ever before. The changes have also led residents in many areas of many cities to consider their neighborhoods less safe than in the past, causing them to respond with inactivity: either they stay inside more or they rely even more on cars to get around.
Even schools have contributed to the trend toward obesity. “Junk food” drinks and snacks are widely available in many schools through commercial vending machines—each one giving a student an extra 150 and 300 unneeded calories per day. More insidiously, perhaps, is the effect of the trend toward high-stakes testing: because of them, many schools tend to strengthen courses and special programs that prepare students in the “basic” subjects that they know will be tested, and to trim programs (like physical education, but also the arts) that will not be tested.
These considerations led a group of physicians at the University of Georgia to organize an after- school program of physical activity for elementary school students (Yin, et al., 2005), and to assess whether the program actually helped prevent weight gain in students. Students volunteered for a program that had three components: 30 minutes of physical activity, a healthy snack, and assistance with the students’ homework. (The researchers explain that assistance with homework had nothing to do with weight loss, but was very important in getting students to attend and getting parents to support the program!) Staff for the program included a mix of regular teachers from the school (not necessarily physical education specialists) and other individuals hired specifically for the project. Physical activities were chosen in part by the students, and were generally non-competitive and cooperative in nature.
Initial results of the program have been very encouraging; students and parents support the program strongly, and teachers have been successful in making sure that students are actually active enough during the program sessions. Since the program is still ongoing, however, it will be a few more years before there will be definitive results about weight gain, or lack thereof.

Questions

➢ It is hard to disagree with the purposes of this study—reducing the prevalence of obesity.
But does it really show what it claims? Be a deliberate skeptic for a moment and ask yourself these questions:
➢ If the students were volunteers, how typical do you think they are of all students?
➢ And if the teachers are receiving a large research grant to implement the program, might they be working harder to do a good job than most of us ordinarily work?
➢ An important ambiguity about the program was the fact that it included both physical activity and homework assistance. Think about this ambiguity.
➢ If the researchers split up these two elements—offering only one or the other at any one school—how might the split affect the outcomes?
➢ Would different sorts of students volunteer as a result of the split, and how if at all would their selection matter?

References
Ogden, C., Flega, K., Carroll, M. & Johnson, C. (2002). Prevalence and trends in overweight among U.S. children and adolescents, 1999-2000. Journal of the American Medical Assocation, 288(14), 1728-1732.
Narayan, K., Boyle, J., Thompson, T., Sorensen, S., & Williamson, D. (2003). Lifetime risk for diabetes mellitus in the United States. Journal of the American Medical Association, 290(14), 1884-1890.
Bawa, S. (2005). The role of the consumption of beverages in the obesity epidemic. Journal of the Royal Society for the Promotion of Health, 125(3), 124-128.Yin, Z., Hanes, J., Moore, J., Humbles, P., Barbeau, & Gutin, B. (2005). An after-school physical activity program for obesity prevention in children.
Evaluation and the Health Professions, 28(1), 67-89