Medscape Pediatrics
Childhood Obesity: Has the Tide Really Turned?
Teasing Out the Real Conclusions From the NHANES Data
Joseph A. Skelton, MDDisclosures
March 06, 2014
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Hi. I'm Dr. Joey Skelton, Associate Professor of Pediatrics and Epidemiology and Prevention at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina. I am also Director of Brenner FIT (Families in Training), which is an obesity research and treatment program here at Brenner Children's Hospital.
I'm here today to talk about the recent publication in JAMA called " Prevalence of Childhood and Adult Obesity in the United States, 2011 to 2012."[1] It was published by Cynthia Ogden and her colleagues at the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.
The big thrust from this study overall has been that obesity prevalence in both adults and children has continued to plateau. It is sort of staying around the same rate. Overall, in children ages 2 to 19 years, obesity prevalence is about 17% (16.9%). In adults, the prevalence has also stayed the same, with an obesity rate of about 35% (34.9%). Overall, the numbers are still the same when you consider overweight and obesity in the United States. About a third of children have a problem with their weight and are overweight or obese. About two thirds of adults have problems with their weight and are overweight or obese.
I am going to focus on the children's data because that has been of big interest. A lot of the discussion about this study has been about a decrease in obesity prevalence in the youngest age group the researchers looked at, which was 2- to 5-year-olds, or the toddler age group. They did do some weight-for-length measurements in infants, but overall, much like the rest of children and adults, there has been no change in prevalence over the past several years.
Overall, this latest set of data found that about 17% of 2- to 19-year-olds are obese. When the researchers looked back at past years, specifically 2003 and 2004, they found that, in that period, about 14% (13.9%) of children 2 to 5 years old were considered obese. The next year, those numbers dropped down to 10.7%, and the prevalence stays at about that range over the next several years. In the years 2009 to 2010, the obesity prevalence in that age group -- again, these are children ages 2 to 5 years old -- is 12.1%. In this past cycle, 2011 to 2012, the obesity prevalence in 2- to 5-year-olds dropped to 8.4%.
The big discussion has been that, when you compare this most recent cycle of NHANES data (with an 8.4% prevalence of childhood obesity in 2- to 5-year-olds) to the period 2003-2004, there has been a huge drop -- from almost 14% down to a little over 8% now. People have noted that that is almost a 50% drop in the prevalence rate, and that is one of the few significant changes that we found over the past 10 years with this data.
A lot of the media has picked up on this conclusion, with headlines saying that obesity rates plummeted in this youngest age group. And that is a good sign. But if you really look a little closer at this data, I would caution that we haven't seen that much change over the past 10 to 15 years.
A past publication, also in JAMA, from the same NHANES dataset in the years 2001 to 2002, documented an obesity prevalence of 10.6% in children ages 2 to 5 years.[2] In the next cycle, 2003 to 2004, that jumped up to 13.9%. And in the next cycle, 2005 to 2006, it dropped back down to 10.7%. That 2003-2004 cycle that was used as a comparator in this most recent publication was really a bump-up in the prevalence. There is some sort of anomaly there that is probably real numbers. This is a very well-done study, but that number went up a lot in that year -- 10% up to 14% and then back down to 10%. If you compare the most recent prevalence of 8.4% to the prevalence in 2003-2004 -- that is a big jump. But if you look across all those years, even going back to 1999 and 2000, when the obesity prevalence in children ages 2 to 5 years was 10.4% also, there has really not been that much of a change. It has stayed around 10%, with that little bump-up in 2003 to 2004, and then most recently in this just-published cycle, down to 8.4%.
I'm throwing out a lot of numbers here and I know that it can be very confusing. But I would say that we must interpret these numbers, and the coverage in the media, very carefully. There really has not been that much of a change over the past decade. There was one year with a really high prevalence and, most recently, there is a positive change, down to 8.4%. The conclusion by Ogden and her colleagues is that over the past 10 years for children ages 2 to 19 years and all adults, there has been no significant change, on the basis of their analysis of the data. There have been no significant changes in obesity prevalence.
So it is great news that this epidemic has seemed to slow down some, but I would definitely not say that the tide is turning. We are starting to see an overall decrease in obesity prevalence. We have a small bit of hope in this youngest group of 2- to 5-year-olds. In tracking BMI (body mass index), there may be a small decrease in this most recent cycle. However, overall I would caution against saying that obesity rates have plummeted in toddlers. The truth is -- much like with all kids and all adults over the past decade -- prevalence has stayed pretty much the same. About a third of children have a problem with being overweight and obese; about two thirds of adults have a problem with being overweight and obese.