To hear some folks talk these days, you would think the childhood obesity epidemic is just about over. At a conference this summer, the Robert Wood Johnson Foundation, the American Heart Association and others were celebrating “Signs of Progress” over childhood obesity. During the Q&A session, a family physician asked what is the broad goal of fighting childhood obesity? The panel appeared thrown by the question and finally rushed to conclude that reversing the childhood obesity epidemic was the goal. That sounds good, like Mom and apple pie. But it got me thinking what does it really mean?
This goal, expressed in similar ways by several public health authorities, is to see no further increases in the prevalence rate of childhood obesity (ages 2-12) based on Body Mass Index (BMI). Lately, some have seen signs of success in the slowing or declines in such rates in some areas. But there are problems with this approach.
First, problems with the BMI itself are well recognized. In particular, we should be concerned that children with high visceral adipose tissue who are very sedentary and consume a poor diet can still have a normal BMI.
Second, by looking at the average or mean BMI in a population, we run the risk of mixing two groups: those who are obesity-resistant and will never become obese and those who are obese and prone to obesity. Studies from outside the United States have shown this pattern.1 By combining the two populations, the average can appear to stabilize even though overweight/obese children continue gaining weight, and a good deal of weight at that.
Third, what does ‘reversing’ the trend mean? Are we going back to the 1995 level, 1985? 1975? 1965? This graph shows the trend lines for US children and adolescents from 1963 to 2008. (Source: Sean Williams, Motley Fool)
The graph does not show the large differences within the age groups by gender, race, ethnicity and geography.
If we are successful at stabilizing or reducing the rates of obesity for children age 2-12 what about the rest of their lives? We know that major weight gain takes place during adolescence and early adulthood. A recent study found 98% of adolescent men and 92% of adolescent women were on upward sloping trajectories for weight gain by middle age. A lower BMI starting point may be good but it is no guarantee of maintaining a healthy weight. 2 While overweight children are more likely to become overweight/obese adults, most obese adults were not overweight as children.
If indeed rates of childhood obesity are shown to be stabilizing or reducing, what is responsible? Are formal childhood obesity prevention programs effective in achieving long-term reductions or stability in body weight? Michelle Obama believes her “Let’s Move” Campaign is responsible for improvements. 3 Likewise, the Robert Wood Johnson Foundation is celebrating its strategies as successful. Unfortunately, the evidence is less clear. A Cochrane Review of prevention programs found a mean difference in favor of childhood obesity programs of a BMI of only -0.15 kg/m2. The review found significant heterogeneity in studies across all age groups and only 8 of the 91 studies reported adverse events, such as unhealthy eating practices.4
A comparative effectiveness research investigation by the Agency for Healthcare Research and Quality found moderate evidence about the effectiveness of school-based interventions for childhood obesity prevention. Physical activity and diet interventions in school settings with home components were effective but few if any studies went beyond one year. 5
What then are clinicians to do? The first step may be to respect the complexity of obesity, now recognized by the American Medical Association and others as a disease. This is not just a problem of willpower. Nor can simple suggestions of “Eat less, Exercise More” be expected to overcome the influence of one’s genetic background, home environment and the role (or dysfunction) of hunger and satiety hormones. Lifestyle changes are likely to be effective in only a subset of children with obesity. 6 Close monitoring and supportive environments are more likely to keep patients motivated to keep working on their weight issues and to be cognizant of the effects of excess weight on their health than critical or stereotyping comments. Greater research, training and education are the keys to resolving the obesity problem not only during childhood but throughout one’s lifetime.
Razak F, Corsi, DJ, Subramanian SV, Change in the body mass index distribution for women: analysis from 37 low- and middle-income countries, PLoS Med 2013;10(1):e1001367, 2013 Jan . 15. Sperrin M, Marshall AD, Higgins V, et al, Slowing down of adult body mass index trend increases in England: a latent class analysis of cross-sectional surveys (1992-2010) Int J Obes 2013 Sep 2. Kautiainen S, Rimpela A, Vikat A, Virtanen SM, Secular trends in overweight and obesity among Finnish adolescents in 1977-1999. Int J Obes Relat Metab Disord 2002 Apr;26(4):544-52.
Malhotra R, Ostbye T, Riley CM, Finkelstein EA, Young adult weight trajectories through midlife by body mass category Obesity 2013 Sep;21(9):1923-34.
http://www.downeyobesityreport.com/2013/02/mission-accomplished-michelle-obama-style/, accessed Nov. 7, 2013.
Waters E, de Silva-Sanigorski A, Hall BJ, et al, Interventions for preventing obesity in children Cochrane Database Syst Rev. 2011 Dec 7;(12):CD001871.
Wang Y, Wu Y, Wilson RF, et al, Childhood Obesity Prevention Programs: Comparative Effectiveness Review and Meta-Analysis. Comparative Effectiveness Review No. 115. http://www.effectivehealthcare.ahrq.gov/ehc/products/330/1524/obesity-child-report-130610.pdf, accessed Nov. 7, 2013
Reinehr T, Lifestyle intervention in childhood obesity: changes and challenges. Nat Rev Endocrinol 2013 Oct; 9(10)607-14.