The prevalence of overweight children in the United States has significantly increased over the past decade. Barlow and colleagues1 report that currently more than 1 in 5 children are overweight or at risk for obesity. It is easy to blame the advancement of technology, the increase in sedentary activities, or other environmental aspects of our current society for the expanding obese population. However, there is a complex relationship between genetic, cultural, and psychological factors that researchers relate to the proliferation of obesity.2
In the United States, the continued growth of obesity in children is economically burdensome--the health care costs for obesity-related diseases such as sleep apnea and cardiovascular disease have tripled over the past 20 years.3 In addition, weight gain can often be emotionally and physically deleterious.3 The continuation of this current epidemic has major implications and consequences for future research in psychopathology.
Obesity is defined by the body mass index (BMI), which accurately reflects the excess body fat of an individual by dividing weight (kg) by height squared (m2). In addition, the BMI demonstrates a strong relationship between body fat and secondary complications of obesity and mortality.4 The National Center for Health Statistics, an organization designed to accumulate statistical information to be used as a resource when drafting health care policies, suggests that any child or adolescent who has a BMI greater than the 95th percentile for his or her age and sex is more prone to remain obese well into adulthood.5 These children are also more likely to experience obesity-related illnesses and higher rates of mortality.4 According to the current literature, a person with a BMI in the 95th percentile is classified as obese, and one with a BMI in the 85th percentile or above is classified as overweight.3
More than 300,000 deaths each year have been associated with obesity and obesity-related illnesses.6 The 1999-2000 National Health and Nutrition Examination Survey (NHANES) reported that more than 15% of children and adolescents aged 6 through 19 years were obese, as were 10% of children aged 2 through 5 years.7 The NHANES also reported the greatest incidence of weight gain among non-Hispanic black and Mexican American adolescents. Between 1988-1994 and 1999-2000, the prevalence of obesity in non-Hispanic black adolescents jumped from 13.4% to 23.6%, while the prevalence in Mexican American adolescents rose from 13.8% to 23.4%.7 In addition, compared with other ethnic groups, African American girls were more likely than any of their counterparts to be obese.5 Faced with the growing epidemic of obesity, psychiatrists should be familiar with certain established relationships between weight gain, obesity, and psychopathology.
A LINK BETWEEN OBESITY AND PSYCHOPATHOLOGY?
Some studies suggest psychiatric comorbidity as a contributor to weight gain and obesity, especially in those with mood, pain, and anxiety disorders.3 However, there are no definitive data at this time that demonstrate a strong relationship between the onset of psychiatric disorders and obesity. For instance, a study by Pesa and colleagues8 showed a significant decrease in the differences in psychopathology between obese and nonobese adolescent girls once body image dissatisfaction was controlled for.
Conversely, a longitudinal study by Pine and colleagues9 demonstrated a significant sex difference in psychiatric comorbidity in adolescents who became obese as adults. Ultimately, the study depicted a positive correlation between depression and obesity in females but not in males. In addition, the investigators found a positive correlation between conduct disorder in adolescence and weight gain in young adulthood. Furthermore, a study by Neumark-Sztainer and colleagues10 reported a higher incidence of suicidal thinking among severely overweight children.Eating disorders
Eating disorders, including anorexia nervosa, bulimia nervosa, and binge eating disorders, are more common in adolescents who are obese. Moreover, overweight adolescents are more likely to partake in chronic dieting behaviors that may lead to unhealthy weight loss as well as poor nutritional intake.10 In 2000, Britz and colleagues11 reported a high incidence of eating disorders occurring simultaneously with mood and anxiety disorders. In several cases, patients believed that their social phobia was directly linked to their weight, while others claimed that mood and anxiety symptoms occurred during or after the onset of their eating disorders.11 With such a high co-occurrence between obesity and psychiatric disorders, it is essential to look at the effects of medications on weight gain (see sidebar: "Psychiatric medications and weight gain").Self-esteem and well-being