Obesity

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15 Obesity

Amanda Jones, Beth Rezet

Obesity is currently one of the most significant health problems in the United States, and the prevalence of this disease is increasing worldwide. A combination of metabolic, genetic, environmental, behavioral, and social factors affects a person’s risk for developing obesity. As the epidemic of obesity increases, there is a concomitant increase in the comorbid diseases associated with obesity, such as diabetes, hypertension, dyslipidemia, nonalcoholic fatty liver disease, sleep apnea, and orthopedic problems.

It is estimated that approximately 15% of children in the United States meet the criteria for being obese. The prevalence of obesity is greatest in children of African-American, Native American, and Mexican American descent. Preventing and treating obesity involve balancing caloric intake with energy expenditure. This basic concept is increasingly difficult in our society given the availability of inexpensive, high-calorie foods and the relatively sedentary lifestyle of most children.

Etiology and Pathogenesis

The causes of obesity are multifactorial, with both genetic and environmental influences playing roles in the balance between caloric intake and energy expenditure. Patients with at least one obese biologic parent have a threefold increased risk of developing obesity in their lifetime; having two obese biologic parents is associated with a 10-fold increased risk for developing obesity. Rarely, a genetic syndrome or endocrine disease contributes to the cause of a patient’s obesity. Examples of these disorders include Prader-Willi syndrome, Cushing’s disease, and hypothyroidism. Evaluation for these causes should be based on physical examination findings and history.

Clinical Presentation

The standardized measurement of weight appropriateness is the body mass index (BMI), which is validated in children older than 2 years of age. Before age 2 years, it is often useful to rely on a patient’s weight-to-height measurement. In adults (age 18 years and older), the term overweight corresponds to a BMI of 25 to 30, and a BMI of 30 or greater correlates with obesity. Throughout childhood, there is both an increase in weight and height, and it is therefore necessary to refer to BMI percentiles, which are adjusted for age and gender:

• Healthy weight: 5% to 85% BMI for age and gender

• Overweight: 85% to 95% BMI for age and gender

• Obesity: >95% BMI for age and gender

BMI is calculated using a formula (weight (kg) ÷ [height (m)]²⁾ or by using a BMI calculator, such as that provided by the Centers for Disease Control and Prevention (http://www.cdc.gov/healthyweight/assessing/bmi/index.html.) BMI should be calculated and plotted on the appropriate standardized graph to ascertain the BMI percentile at every well-child visit.

The history and physical examination of an obese patient should focus on identifying the problem, treatment options, and comorbidities. To assess for a patient’s risk for or diagnosis of obesity, one inquires about a patient’s lifestyle, including a general assessment of the patient’s dietary and eating habits, with particular attention placed on consumption of fruits and vegetables as well as high-calorie foods that are low in nutritional value, such as sweetened drinks, and an assessment of the patient’s daily screen time (both television and video games) and physical activity. Family history should include any first-degree relatives with obesity or common comorbidities of obesity, such as hypertension, cardiovascular disease, diabetes, and liver disease.

Laboratory evaluation such as fasting glucose, liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST]), and fasting lipids are used to screen patients for the common comorbidities associated with obesity. Additional tests should be ordered based on the history and physical examination (Table 15-1).

Table 15-1 Evaluation for Comorbidities Associated with Obesity

Management

Prevention

Pediatric prevention of obesity starts at birth, encouraging the current recommendation that infants be breastfed for at least the first 6 months of life. Helping parents to respond to satiety cues will encourage healthy eating habits. Early emphasis on healthy habits relating to food and physical activity allows parental control over some environmental factors. Establishing these habits early can lead to a lifelong preventive approach.

Treatment Options

Behavioral

The management of obesity requires a multidisciplinary approach and should involve the patient’s family in all aspects of treatment planning. Research provides evidence that behavior modification is the most useful modality in the treatment of pediatric obesity. It is essential to use motivational interviewing and consider the readiness of the patient and his or her family in adopting the lifestyle changes necessary for management of obesity. Lifestyle interventions can focus on any or all areas of a child’s life: home, school, and childcare settings (Figure 15-1).

Figure 15-1 Treating obesity.

Excessive television viewing has been linked with obesity. This is most likely to be a combination of the sedentary nature of passive viewing as well as the commercial advertising of high-calorie foods. Reducing the number of hours of screen time, including television, video games, texting and computers, may have a significant effect on lowering a child’s risk of obesity.

The American Heart Association has published recommendations for diet and exercise for children age 2 years and older. These include a diet rich in fruits, vegetables, whole-grain breads, and cereals with only a limited amount of juices, sugar-sweetened beverages, and processed foods. Children can easily consume excess calories in the form of beverages, and it is therefore important to follow current recommendations that include limiting juice intake to 4 to 6 oz/d, to include three servings of milk (whole milk until 2 years of age and then skim or 1% thereafter), and to frequently offer water (after age 6 months). Additionally, it is suggested that parents concentrate on limiting portion sizes and refer to nutritional labels when serving and preparing meals (see Figure 15-1).

Many children eat at least one meal daily that is provided by school. Meals that are available through government-subsidized programs are subject to nutritional standards based on adequate daily caloric content and not necessarily on low sugar, low fat, or high fiber. Additionally, there are many other foods offered “a la carte” and through vending machines and snack bars in schools that are not as well controlled for nutritional content. Efforts have been made in recent years to enact nutritionally sound policies for both government subsidized meals and other foods offered during the school day.

For a number of reasons, over the past 30 to 40 years, schools have dramatically decreased their curriculum involving physical activity. Recent recommendations have included the addition of 60 minutes of vigorous physical activity in an average school day (see Figure 15-1).

Pharmacologic

Pharmacologic treatment of obesity could be considered as an adjunct to dietary and behavioral modifications in older children and youth. The medications approved for use in the pediatric population are orlistat and metformin, the latter of which is not specifically approved for the treatment of obesity.

Orlistat (Xenical) inhibits the absorption of fats by reversibly inhibiting gastric and pancreatic lipases. Adverse effects of Orlistat include abdominal discomfort and diarrhea. Metformin (Glucophage) is approved for use in type II diabetes, decreasing endogenous glucose production and inducing peripheral insulin sensitivity. It may also be prescribed for the treatment of women with polycystic ovarian syndrome. Appetite suppressants such as amphetamines and antidepressants associated with appetite suppression are not currently approved for pediatric use.

Surgery

The term bariatric surgery refers to various procedures that have been shown to produce long-term weight loss results and reduction in obesity-related comorbidities. It is an established treatment option for adults with morbid obesity, defined as BMI of 40 or greater. These procedures include those that induce a state of malabsorption and those that restrict a patient’s intake by decreasing stomach size. Currently, the two procedures offered in the pediatric population are gastric bypass with roux-en-Y anastomosis and gastric banding. Bariatric surgery is only considered for children at least 13 years old with BMIs of 40 or greater and comorbidities associated with obesity and for whom other treatment options have failed. It is also important that patients undergoing this form of treatment be committed to following strict nutritional guidelines and medical follow-up required after surgery.

Future Directions

There is a need for strong evidence-based recommendations in the prevention and treatment of pediatric obesity. It is clear that this will be multifactorial involving dietary, physical activity, environmental, and policy interventions with individual and community support for patients and families.

Suggested Readings

Baranowski T, Berkowitz R, et al. Available at http://www.nhlbi.nih.gov/meetings/workshops/child-obesity/

Barlow SE. the Expert Committee: Expert Committee recommendations regarding the prevention, assessment, and treatment of child and adolescent overweight and obesity: summary report. Pediatrics. 2007;120(suppl):S164-S192.

2006 Woodrow Wilson School of Public and International Affairs at Princeton University and the Brookings Institute: Childhood Obesity. The Future of Children. 16(1), 2006.

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