Co-Morbidities of Childhood Overweight

Discussions of childhood overweight often concentrate on the likelihood that children who are overweight will become diabetic or will grow up to be obese adults, but some health problems are more immediate, says a physician writing in the current issue of the journal The Future of Children.

"The epidemic of overweight and obesity in children and adolescents has intensified the pace of research" into the question of whether children face the same set of risks as adults—or risks unique to their age group—from those conditions, says Dr. Stephen Daniels, a professor of pediatrics at the University of Cincinnati College of Medicine.

To get a handle on that question, Daniels assessed disorders related to childhood obesity by body systems and estimated their prevalence in pediatric populations. Among his findings:

• The Cardiovascular System. Until recently, most medical concerns about children’s hearts involved birth defects, but advances in noninvasive testing have made it possible to evaluate children’s hearts and blood vessels, and recent research has demonstrated that the odds of elevated blood pressure—a major risk factor for heart attack—are significantly higher for children whose body mass index (BMI) is at or above the 90^th percentile. Also of importance is left ventrical hypertrophy, or increased thickness of the heart’s main pumping chamber, which is also linked to BMI. And fatty streaks associated with hardening of the arteries have been found at autopsy in overweight children.
• The Metabolic System. The metabolic syndrome is a constellation of risk factors, including increased waist circumference, increased levels of "bad" cholesterol, and insulin resistance. Type 2 diabetes, long linked to obesity in adulthood, is now appearing in children as young as eight years and has increased dramatically in adolescents. A recent study found the metabolic syndrome in only 4 percent of all children but in 30 percent of children who are obese.
• The Pulmonary System. Some studies have shown a link between overweight and asthma in children. It’s not clear why that is so, but researchers speculate that obesity may increase inflammation, which contributes to asthma, or children with asthma may become overweight because they have reduced physical activity. There is a close relationship, however, between obesity and another pulmonary disorder, sleep apnea, which can result in daytime sleepiness and poor academic performance. One study found that a third of severely overweight young persons had symptoms associated with obstructive sleep apnea.
• The Gastrointestinal System. Researchers have found that the same processes of fat deposit and inflammation that cause liver disease and reflux disease in adults can afflict children and adolescents, though it’s hard to get evidence of these conditions. Liver disease has no symptoms and is often discovered in autopsy, but researchers believe as many as 50 percent of obese children may have fat deposits in their livers.
• The Skeletal System. Some complications of obesity are physical—the effect of body weight. Orthopedic problems that affect obese children include Blount disease, a mechanical deficiency in the growth plate in adolescents that results in a bowed appearance of the lower leg and abnormal gait; it most commonly affects boys over nine years of age who are overweight. Another orthopedic problem related to overweight in young patients is an abnormal rotation of the bone in the upper leg and hip that requires surgical repair; it is most common in overweight males and African-Americans.
• Psychosocial Issues. Depression is a common mental health problem in adolescents and its relationship to overweight is not well known, but among some girls the cause of depression is body dissatisfaction, leading to dietary restraint and symptoms of bulimia. Evidence is mixed on whether overweight children have good peer relationships. Ongoing research is looking at how, specifically, obesity affects children’s lives, but one study found that overweight children and adolescents were five times more likely than their normal-weight counterparts to report impaired quality of life in general and poor health quality of life in particular.

In a discussion of the long-range implications of his findings, Dr. Daniels notes that "With overweight and obesity such serious health risks for adults, an important question is whether overweight children retain their relative ranking related to their peers as they age and become adults." Studies seem to confirm that obesity in very young children, aged one or two, is not associated with adult obesity, but for children older than two and for adolescents, the odds of becoming an obese adult were higher and increased the higher their BMI was and the older they were when they became obese as children. It has also been found that having an obese parent makes it more likely that an obese child will continue to be obese into adulthood.

And whether one looks at the immediate effects on children’s health of being overweight or the implications of that overweight for the future adult population, "Preventing childhood obesity is of urgent importance," Dr. Daniels concludes.

The article "Consequences of Childhood Overweight and Obesity," appears in the Spring 2006 issue of The Future of Children, a publication of the Woodrow Wilson School of Public and International Affairs at Princeton University and the Brookings Institution and is available online at www.futureofchildren.org

Note: The Future of Children uses the terms "overweight" and "obesity" interchangeably to mean a range of body mass index percentiles.

See also: Childhood Overweight: What the Research Tells Us at http://www.healthinschools.org/sh/obesityfs.asp and Keeping Kids Healthy: Overweight, Nutrition & Physical Exercise at http://www.healthinschools.org/sh/obesity.asp.