Childhood obesity: Curbing an American epidemic

The number of overweight children in this country has increased more than 50% in just one generation. Whether they work in primary care or specialty practices, PAs are first responders in this new public health emergency.

Diana Taylor Noller, MSPT, MMS, PA-C; David Paulk, MS, PA-C

Diana Noller works at Reconstructive Orthopedics in Burlington County, NJ. David Paulk is Academic Coordinator for the PA program at Arcadia University, Glenside, Pa. They have indicated no relationships to disclose relating to the content of this article.

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The modern American lifestyle, comprised primarily of sedentary activity and a diet high in calories, has produced an epidemic of alarming proportions in today’s youth: obesity. Childhood obesity is a health concern of great magnitude. It demands significant attention from health care providers because of the adverse effects that obesity can have on health throughout the life span of those affected.  

Overweight or obese?

There are no universal definitions for the classification of overweight and obesity in children. Obesity is most often determined by calculating body mass index (BMI): the ratio of weight in kilograms to the square of height in meters.

Since BMI does not distinguish between adiposity and increased lean body mass, clinicians should consider body habitus when using BMI to diagnose obesity. When used to classify obesity in children, the BMI has been correlated with comorbid, obesity-related conditions.¹ A child with a BMI between the 85th and 95th percentile for age and gender is often considered overweight, while one with a BMI greater than the 95th percentile is considered obese.¹

By this classification, an estimated 21% to 24% of children and adolescents in the United States are overweight, and 10% to 11% are obese.² The number of overweight children has increased by an estimated 50% to 60% in just one generation.² This is a crisis whose public health and economic implications are enormous. Preventing obesity is the key, and preventing childhood obesity begins with recognizing those children at greatest risk. 

Risk factors for obesity

Obesity, the excess deposition of adipose mass, results when total energy consumption surpasses total energy expenditure. The imbalance of energy intake and expenditure resulting in weight gain is a complex process and is a consequence of the interplay among genetic, physiologic, metabolic, social, behavioral, and cultural factors.³

Genetic, physiologic, and metabolic factors A family history of obesity puts a person at risk for developing the condition. It had been thought that the association between obesity and family history stemmed from shared environmental factors. Recent research suggests, however, that there is a link between genetic makeup and obesity. Twin studies have shown that being overweight is a 65% to 75% inherited trait.⁴ If a young child has one obese biological parent, the odds ratio is roughly 3 for that child to be obese in adulthood; if both parents are obese, the odds ratio of obesity in adulthood is greater than 10.¹ Genetics influence basal metabolic rate, feeding behavior, alterations in energy expenditure in response to overfeeding, lipoprotein lipase activity, and basal rate of lipolysis.⁴

Hormones and neurotransmitters such as growth hormone, leptin, ghrelin, neuropeptide Y, and melanocortin regulate satiety, hunger, lipogenesis, and lipolysis; these probably contribute to a person’s risk for becoming obese, although their roles are not yet clearly understood. Further research is needed on the genetic basis of these substances and how they affect weight gain in order to develop more effective ways of treating obesity.

Some genetic and endocrine disorders play a role in dysregulation of energy expenditure versus intake, resulting in weight gain: Prader-Willi syndrome, Bardet-Biedl syndrome, Alström syndrome, hypothyroidism, and Cushing’s syndrome all create a propensity toward obesity.

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Social and behavioral factors The recent surge in childhood obesity cannot be explained by genetics alone.⁵ There have been societal changes over the past few decades that place American children at increased risk for being overweight and obese.

When the physiologic basis of weight gain is considered, the current lifestyle trends that place children at greatest risk for obesity are clear: decreased physical activity and increased caloric consumption. In the twin studies, environmental differences throughout childhood accounted for nearly 30% of the variance in body weight.⁶

Regular exercise is beneficial to overall health and weight control. It regulates weight by allowing direct energy expenditure during exercise, increasing the metabolic rate during and immediately after exercise, increasing lean body mass, and, in turn, raising the resting metabolic rate.³ When considering the benefits of exercise, clinicians should also bear in mind the unfavorable effects lack of regular exercise has on a child’s health and well-being.

The amount of time children spend daily watching television and playing video games has increased over the past decade and is significantly correlated with the development of childhood obesity. In a national survey, 20% of children aged 8 to 16 years reported participating in two or fewer episodes of vigorous exercise per week, and more than 25% watched television for 4 or more hours daily.¹ The average child watches 3 to 5 hours of television a day.⁶ According to the American Academy of Pediatrics (AAP), children who view television for more than 4 hours daily have significantly greater BMIs than their counterparts who watch television less than 2 hours a day. In addition, placing a television in a child’s bedroom is a strong predictor of future overweight, even in young children.¹

The urbanization of America also contributes to the problem. National transportation data suggest that walking and bicycling among children aged 5 to 15 years decreased 40% from 1977 to 1995.⁶ The recent reductions in mandatory school physical education classes further lowers physical activity. In fact, daily participation in high school physical education decreased from 42% to 29% between 1991 and 1999 alone.⁶

An enormous amount of television advertising for sugary cereals, fast foods, candy, and soda targets children. The increased consumption of these high-density foods further contributes to the epidemic of childhood obesity. The Third National Health and Nutrition Examination Survey (NHANES III) found that the rate of soda consumption among adolescent males increased almost 65% from 1989 to 1995.⁶ This is alarming given the findings that drinking soda correlates directly with obesity.

Several researchers have suggested that the diminishing number of families eating meals together in recent decades has played a role in increasing childhood obesity. Studies show that the absence of family meals is associated with reduced fruit and vegetable intake and increased consumption of fried food and soda.¹

Environmental factors Several environmental factors contribute to childhood obesity. Studies show that children growing up in home environments that fail to provide adequate cognitive stimulation have more than a two-fold increase in the risk of developing obesity.⁶ Furthermore, the obesity risk is increased two to three times among children from nonsupportive home environments and ninefold among children who have been neglected.⁶

In addition to investigating the effect of present environment on the development of obesity, researchers have identified past environmental influences on the propensity for obesity. For example, infants of mothers with diabetes are at increased risk for developing obesity in childhood.⁷

Interestingly, the extent and duration of breastfeeding correlates inversely with the risk of subsequent obesity in childhood.¹ This is believed to be the result of physiologic factors in human milk, along with feeding and parenting patterns related to breastfeeding.¹  

The ethnic and socioeconomic divide

The most current information from the National Longitudinal Survey of Youth (NLSY) depicts a grim picture of obesity among African-Americans and Hispanics. The rate of childhood obesity is increasing 47% to 73% faster among these two ethnic groups than among the white population.⁶ The Child and Adolescent Trial for Cardiovascular Health, which longitudinally followed more than 5,000 children of ethnically diverse backgrounds, found that being of African-American descent was a strong predictor of being overweight by age 11 years.⁸

The factors contributing to this ethnic divide are complex and likely stem from socioeconomic and cultural differences. The poverty rate among African-Americans and Hispanics is roughly three times higher than that among whites.⁸ Many studies have found an inverse relationship between family income and obesity. Furthermore, nutrient-poor foods are often more affordable than those rich in nutrients. For example, the inflation-adjusted price of fresh fruit increased 54% between 1986 and 1998, while the price of fresh vegetables went up 34%.⁶ In contrast, the inflation-adjusted price of soft drinks decreased 22%, along with the price of sugar, snacks, fats, and oils.⁶ Many children in urban areas lack a safe area outdoors in which they can run, ride bicycles, and play, so they stay inside near the temptations of television and video games. When they do go outside, the neighborhood fast food restaurants are far too enticing.  

The effects of obesity in childhood

Obesity increases the risk, in childhood, of pulmonary, cardiovascular, neurologic, orthopedic, GI, endocrine, and psychological disorders (see Table 1). The likelihood of adult illnesses such as cardiovascular disease, stroke, and colorectal cancer is also greater, and overall life span is decreased.²

Pulmonary Childhood obesity increases the risk of obstructive sleep apnea, which has been identified in obese infants as young as 6 months old.⁹ As many as 59% of obese children with a history of snoring, nighttime awakening, orthopnea, difficulty awakening in the morning, and daytime somnolence were found to have sleep apnea.⁹ Causes may include greater fat mass, increased muscle relaxation, and enlarged tonsils and adenoids.⁹

The deleterious effects of sleep apnea include poor school performance, lack of concentration, pulmonary hypertension, systemic hypertension, cor pulmonale, and right heart failure.⁹ There is a significant correlation between fasting insulin levels and sleep apnea. If left untreated, obstructive sleep apnea may lead to respiratory failure and death.

Cardiovascular Childhood obesity is associated with many physiologic changes that increase the risk for adverse cardiovascular events, such as the development of type 2 diabetes, dyslipidemia, hypertension, and cardiomyopathy of obesity. Recent research has found that the metabolic syndrome (a combination of insulin resistance, obesity, hypertension, and hyperlipidemia) can actually begin in childhood. Evidence that the metabolic syndrome poses a potent risk for atherosclerotic cardiovascular disease is plentiful. Elevated levels of circulating insulin, insulin resistance, or perhaps a combination of both may be central to this risk. An encouraging finding is that even modest weight loss (5%-10% of body weight) can reverse insulin resistance and its adverse effects.⁴

Neurologic Some children with obesity-related sleep apnea have neurocognitive deficits. These manifest as a reduction in attention, motor efficiency, and graphomotor ability.⁹

Orthopedic There is a clear relationship between obesity and a slipped capital femoral epiphysis (SCFE), which occurs when the proximal femoral epiphysis separates from the femoral neck through the growth plate. SCFE is considered an orthopedic emergency because of the risk of avascular necrosis of the femoral head, which is seen in up to 30% of these children.^7,9 Patients with SCFE have a high incidence of premature degenerative joint disease even when they do not develop avascular necrosis.⁷

GI One in five obese children has liver dysfunction, evidenced by elevated plasma transaminase levels.² The dysfunction usually results from hepatic steatosis, but fibrosis and cirrhosis may occur if obesity is not reversed. Weight loss may prevent progression of the dysfunction, reduce transaminase levels, and improve steatosis.⁹

Endocrine As discussed previously, the hyperinsulinemia and insulin resistance caused by obesity may lead to the development of type 2 diabetes in childhood. This is a serious health concern facing many overweight children today, as the lifetime effects of the disease are numerous and potentially devastating. Polycystic ovary syndrome can also be a complication of hyperinsulinemia and insulin resistance. Multiple immature follicles form on the ovaries of affected girls, who may have hirsutism, anovulation, and infertility. Modest weight loss can reverse these effects.

Psychosocial Throughout their lifetime, obese children are likely to suffer from low self-esteem, depression, and anxiety, which can impair their ability to grow and thrive. For instance, overweight females are more likely to complete fewer years of school, are less likely to get married, and are more likely to live in poverty than are their normal-weight counterparts.²  

Treating childhood obesity

Clinicians should screen all children presenting for annual physical examinations by measuring height and weight and calculating and graphing BMI. In addition, they should have an honest and detailed conversation with the child and parents to gain a clear understanding of eating and physical activity behaviors in order to provide appropriate counseling.

Before making a diagnosis of primary obesity, the PA should rule out disorders that can cause secondary obesity, as listed in Table 2. Since these disorders are associated with additional health risks, recognizing them early is crucial. Once a diagnosis of obesity without a causal disorder is made, immediate intervention involving both child and family is essential, through education, appropriate screening, and prompt referral.

Timely treatment is imperative because as an obese child grows, the risk of becoming an obese adult increases. Estimates are that 26% to 41% of obese preschoolers remain obese in adulthood, and 42% to 63% of obese school-age children will grow into obese adults.² Determinants of treatment success include strong social support, parental involvement, and an understanding that changes must be lifelong.⁴ Working with these patients allows PAs to help children and their families make momentous lifestyle changes which will lend lifetime benefits.

Dietary improvement encompasses decreasing caloric consumption while improving the quality of foods. Aim for a slow, progressive weight loss rather than a drastic weight change, whose effect on a child’s growth is unclear. Ideally, a qualified nutritionist should involve the child and other family members in counseling. If no nutritionist is available, the PA can educate the family on recipe modification, selecting healthful foods while grocery shopping, and learning which foods are advisable and which foods should be limited. Parents should be aware that they are the role models for their children; thus, they must exemplify desired eating behaviors themselves.

Exercise increases energy expenditure, decreases body fat, improves lipid profiles, and increases lean body mass, all of which aid weight loss and improve health and well being. PAs should identify barriers to physical activity and work with patients and their families to develop strategies to overcome these obstacles. In addition, children should limit time with television and video games to less than 2 hours daily.

Cognitive behavior therapy (CBT) strives to alter attitudes about eating, body image, and weight loss. Its premise is to set attainable goals that will be reached by modifying current behaviors. This is partially accomplished by establishing stimulus control, in which exposure to cues that prompt overeating is limited, access to high-calorie foods is restricted, and improved behaviors are adopted.³ A reward system encourages achieving established goals. Research has shown that children treated with this approach before the onset of puberty realize a significant improvement in weight management.³ One 10-year follow-up study of patients treated before puberty found that 30% were no longer obese and 34% had a decrease in percentage of overweight.³

Other, more drastic means of treating obese children, such as surgical or pharmacologic interventions, are not generally recommended except in extreme cases resistant to other means of treatment. Recently, gastric bypass surgery has been suggested as a last-ditch way to achieve substantial weight loss in severely obese children. Because this surgery may interfere with skeletal development by reducing calcium absorption, it may be best reserved for children older than 15 to 17 years so that adequate bone mass can be achieved before surgery.¹⁰ Even then, the long-term effects of gastric bypass surgery on bone health in these young persons is unknown. 

The screening debate

Screening for hyperlipidemia is recommended for children with obesity and one additional risk factor, such as a family history of hyperlipidemia or lack of physical exercise, because timely treatment improves outcomes. The first-line treatment in children with hyperlipidemia is a diet low in saturated fats and high in soluble fiber, along with increased physical activity. If diet is unsuccessful, bile acid-binding resins have been shown to be effective, although problems with adherence exist.¹¹ The use of statins in children older than 10 years has shown good efficacy and compliance when used for up to 2 1/2 years.¹¹ However, all of these trials have been underpowered for safety in this population. For this reason, statins should be used cautiously in children, weighing the risks of hyperlipidemia against the potential risks of long-term treatment with these medications.

Population-based screening for type 2 diabetes in high-risk children, on the other hand, is more controversial. In fact, the AAP does not recommend population-based screening even in high-risk children and in those with signs of insulin resistance because evidence from controlled trials does not support the premise that earlier diagnosis improves long-term outcomes.¹² Currently, the sensitivity, specificity, and cost-benefit ratio of screening high-risk children are being studied to determine the appropriateness of this recommendation. The impact that screening would have on the early management of these children is also in question. First-line treatment of children with type 2 diabetes involves improving diet and increasing physical exercise. In fact, the Diabetes Prevention Program showed that diet and exercise interventions delay the onset of the disease and normalize blood glucose levels.¹² This underscores the importance of the recommendation that all children at high risk for developing diabetes and those with signs of insulin resistance be counseled early about the importance of maintaining a healthful lifestyle.  

Preventing obesity in children

Since achieving long-term weight loss is often unsuccessful, preventing childhood obesity is key to curbing this modern-day epidemic. The importance of preventing obesity in children is exemplified by evidence that, when followed long term, 80% to 90% of obese children who lost weight returned to their original weight percentile.⁴ Prevention can be achieved at the individual level by instituting proper eating and lifestyle habits, but most successful efforts will need to come from public health initiatives and societal changes.

The direct costs of obesity represent 7% of the total US health care expenditure, and preventable morbidity and mortality related to obesity is predicted to surpass those associated with cigarette smoking.^1,5 Health care providers can do many things on a public health level to promote changes that decrease the burden obesity places on the lives of those affected, as well as on society as a whole.

The role of schools In schools, improved strategies to prevent childhood obesity can be implemented, particularly in the areas of health education, physical education, and the food environment. Schools should emphasize the detrimental effects of obesity and the importance of adopting healthful eating and lifestyle habits. Education regarding goal setting, ways to institute behavioral change, and an emphasis on maintaining positive change for the long term should be included.¹

Unfortunately, many schools serve cafeteria food that is high in calories, fat, and sugar and stock vending machines with soda and unhealthful snacks. For instance, 35% of the calories in an average school lunch are from fat—a percentage that exceeds the recommended maximum of 30%.⁵ Studies have shown that high-fat foods such as potato chips, nachos, french fries, and cookies are among the best-selling items in junior high and high schools. This is alarming given that children often consume a large proportion of their total food intake at school. Schools must recognize the importance of offering healthful food alternatives while decreasing the availability of foods high in calories, fat, and sugar.

Mandating student participation in physical education promotes expectations and develops social norms for frequent and regular exercise.⁵ However, only Ohio currently requires daily physical education in grades K through 12.⁵ In order to promote regular, vigorous physical activity, schools must shift away from sports-focused physical education and toward health-related physical fitness and require more regular participation in physical education among all school-aged children.⁵

Provider reimbursement Paying clinicians for obesity prevention and treatment services should be another public health priority. Providers do not typically focus on prevention because they are not likely to be paid for doing so; lack of reimbursement thus represents a major barrier to weight-reduction management in the primary care setting.⁵ Obesity prevention and treatment services are likely to increase if clinicians are given incentives to provide them.

The role of the clinician The effectiveness of interventions to prevent and treat childhood obesity depends on the actions of the child, family, and health care provider. The task facing them is a difficult one. A team approach with adequate medical and psychosocial support is essential for success. The clinician’s role is to empower children and their families to make long-term behavior changes, to support public policy changes, and to provide the necessary resources to ensure the best quality of life for these children.   

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