Childhood Obesity

Endocrine Society Symposium
Thursday June 17, 2004
3:45 – 5:45 PM

Reviewed by Joelle Escoffery, PhD

The goal of this symposium was to review the scope of obesity in childhood, as well as to evaluate different treatment options.  Unlike overweight in adults, childhood overweight is defined by body mass index (BMI) referenced for age. Childhood overweight is defined as a BMI of greater than or equal to the 95^th percentile, and risk of overweight is defined as a BMI between the 85^th and 95^th percentiles.  These values were selected because they approximate BMI of 25 and BMI of 30, the values that define overweight in adults. The prevalence of overweight among children has tripled in the past four decades, with 15% of children currently meeting the criteria for overweight.  Among children between the ages of 6 and 11, prevalence of overweight has tripled, with greater increases seen in African American and Mexican American children. Prevalence of overweight in children under the age of 5 is greatest among Hispanics and Native Americans, with little difference between African Americans and Caucasians in that age group. The increasing prevalence of obesity in childhood is particularly disturbing in light of evidence demonstrating that BMI in childhood tracks to adulthood. 

Because of the epidemic nature of obesity in childhood, a variety of different treatment approaches are being investigated.  The “conservative state of the art” for the treatment of childhood obesity is a lifestyle treatment that consists of a 500 Kcal/day deficit in diet, increases in physical activity and concomitant decreases in physical inactivity, and extensive behavior modification strategies such as self-monitoring, positive reinforcement, and cognitive restructuring.  Although this approach has shown an approximate 25% decrease in overweight after a year, the decrease in overweight drops to 7% by 10 years. Because of the lack of long-term success, pharmacologic therapy for the treatment of childhood obesity has begun to be explored as an adjunct to lifestyle changes.  Pharmacologic therapy may be considered in this group if BMI is greater than the 95^th percentile, lifestyle change has not been effective, and comorbid conditions are present.  It is important to note that most pharmacologic therapies are not approved for use in children, and should not be used outside of clinical research.  In terms of drugs that affect food intake, the serotonin and norepinephrine reuptake inhibitor sibutramine has been shown to be reasonably effective at promoting weight loss, but it has also been shown to cause increases in blood pressure. The lipase inhibitor orlistat has been shown to have a modest effect on weight loss, but it is associated with GI side effects that may limit adherence.  Orlistat is the only pharmacologic weight loss agent approved for use in children between the ages of 12 and 16. Metformin has also been shown to be useful for weight stabilization while also decreasing hepatic glucose production.

In terms of diet therapy for the treatment of childhood obesity, reducing dietary fat may not be the most effective strategy for weight loss.  Accordingly, other dietary approaches, such as the use of the glycemic index (GI), have begun to be investigated.  The glycemic index is an empirical measure of the rate of carbohydrate digestion. Low GI diets have been shown to be associated with decreased appetite, a more favorable waist-to-hip ratio, and improvements in BMI.  They may also be beneficial effects to people with diabetes, as high GI diets have been associated with increased free fatty acids and postprandial hyperglycemia.  A low GI diet also represents a middle ground between the low fat and low carbohydrate approach to dieting.