Morbid Obesity in Children

In pediatrics, the term “obese” generally refers to children whose weight weight for height (or Body Mass Index—BMI) is greater than the 95th percentile for their age and gender (notably, some institutions instead refer to this group as “overweight”). The complications of morbid obesity span multiple [Page 474]organ systems and include such disorders are hypertension, Type 2 diabetes mellitus, obstructive sleep apnea, and many others. Treatments for morbid obesity include lifestyle modification, pharmacologic therapy, and in the most extreme cases, bariatric surgery.

Definition

In pediatrics, the term obese generally refers to children whose weight is greater than the 95th percentile for their age and gender (notably, some institutions instead refer to this group as “overweight”). While no specific percentile is delineated to classify a child as “morbidly obese,” the term is generally used to identify those children whose risk of obesity-related illnesses is dramatically increased compared to other obese children.

Prevalence

The term morbid obesity is not officially recognized in the pediatric population by the U.S. Centers for Disease Control and Prevention (CDC). Thus, accurate statistics to measure the prevalence of morbid obesity in U.S. children are not available. However, based on statistics from 1999 to 2004, the prevalence of BMI above the 95th percentile (referred to by the CDC as “overweight” and by other institutions as “obese”) in children and adolescents increased from 13.9 percent in 1999–2000 to 17.1 percent in 2003–04. Research indicates that the prevalence of morbid obesity increases significantly faster than obesity alone (this research was compiled from adult research subjects), so the prevalence of morbid obesity in children is likely increasing as fast, if not faster, than obesity.

Epidemiologic data on morbid obesity are not currently available. However, the data for obesity alone in 2003–04 indicate that 16.3 percent of Caucasian children, 19.2 percent of Mexican-American children, and 20.0 percent of African-American children were above the 95th percentile for BMI.

Causes

The cause of morbid obesity in childhood is unclear. However, many researchers believe that morbid obesity is simply an extreme form of obesity and is thus subject to many of the same risk factors. The specific risk factors for childhood obesity are innumerable, but can be easily grouped into categories of genetic or inborn versus environmental risks. The genetic contribution to obesity is estimated to be anywhere from 25–70 percent, while the environmental contribution can vary in the same manner. However, most experts agree that much of the increase seen in obesity over the last 30 years has been due environmental risk factors as sedentary lifestyle (television watching, video game playing, etc.), large portion sizes, and the consumption of high-calorie, high-fat food. Limited education, the cessation of smoking, and lower socioeconomic status are also associated with increased risk of obesity.

Genetic and endogenous factors also appear to play a role in obesity. Various family, adoption, and twin studies have demonstrated a strong genetic component to becoming obese. Mutations in certain genes such as the beta-3-adrenergic receptor gene and the peroxisome-proliferator-activated receptor (PPAR) gamma 2 gene have been associated with altered protein function that is believed to contribute to weight gain. In addition, metabolic, neurologic, and endocrine factors are also associated with obesity; those individuals with lower metabolic rates, lower levels of sympathetic nervous system activity, problems with insulin resistance, and dysfunction of the dietary feedback control system (involving such chemicals as ghrelin, leptin, and melanin-concentrating hormone) are all at an increased risk of becoming obese.

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