Learning Objectives

The reader will be able to:

• Describe the prevalence of childhood obesity in the US and globally.
  
• Define overweight and obesity in children
  
• Describe the main biological outcomes of obesity in children
  
• Identify the biological outcomes of obesity unique to children
  
• Explain the two main social outcomes of childhood obesity
  
• Describe the two main cognitive and psychological outcomes of childhood obesity

Introduction to Childhood Obesity

The prevalence of overweight in children is high and consistently rose from 1980 to 2002, in the US and worldwide. Currently nearly 34% of US adults are obese: the percentage more than doubled in the past 30 years and prevalence has more than tripled in children and adolescents 6–19 years old (1) To classify children for weight risk, the BMI percentile for age and sex is used in 2–19 year olds. Recently revised definitions classify a child with a BMI at the 85th–<95th percentile as “overweight”; a child with a BMI at the 95th percentile or higher is “obese” (2) (see Table 11-1). Infants and toddlers are classified as overweight at a weight for recumbent length equal to or above the 95th percentile. In 2007–8, 32% of those 2–19 years old, and 9.5% of infants and toddlers, were overweight. According to the National Health and Nutrition Examination Survey (NHANES) (3), 17% of all children ages 2–19 years, of a nationally representative sample of the US population, were obese. Although the percentage of children who are obese has remained constant for the last several years, the average BMI among these obese children has continued to rise. In other words, the heavy have gotten heavier. With that rise is a concomitant increase in prevalence of an expanding list of comorbidities, many of which were not previously reported in children (3).

Table 11-1 BMI Categories for Children and Teens

Globally, obesity affects nearly as many children as does under-nutrition. Researchers have analyzed a variety of published medical reports on obesity from 1980 to 2005, as well as World Health Organization (WHO) data (4). They tracked the rate of obesity in school-age populations in 25 countries and in preschoolers in 42 countries, and concluded that the prevalence of childhood obesity increased in almost all the countries studied. They predict that nearly half of the children in North and South America will be overweight in the next decade and about 38% of all children will be overweight in the European Union. One in five children will be overweight in China, and in most Middle Eastern and South Asian countries. With this significant increase in the number of overweight children worldwide, scientists expect profound effects on everything from public healthcare to economies. Thus, the importance of addressing obesity in young people stems from the significant ramifications for future illness, as well as the more immediate medical and psychological problems during childhood.

Measurement and Definition Issues Unique to Children

Determining excess weight in children is complicated. BMIs in childhood are lower than in adulthood, rising to adult levels with maturation. Furthermore, rapid growth, especially in adolescence, can sometimes result in a decrease in BMI. As indicated above, according to current recommendations of the American Academy of Pediatrics (AAP), children’s BMI percentiles for age and sex are used to classify them as overweight or obese.

BMI

The usual early risk indicators of overweight are physical size and growth rate. Most children are measured during healthcare visits and the values are plotted on growth charts, but BMI, necessary to identify a pattern indicating risk of obesity development, is not generally calculated or plotted. Beginning at age 2 and continuing through age 20, healthcare providers should regularly and carefully measure the child’s weight and height and calculate the BMI in order to identify children who are overweight or obese. The 2000 CDC BMI charts are used for plotting BMI against the age (in months) of the child to determine the sex- and age-specific BMI percentile. These charts are based on a representative, ethnically diverse sample of US children 2–20 years of age. They use weight, height, age, and sex to classify a child as underweight, at a healthy weight, overweight, or obese as shown in Table 11-1. See Chapter 1 for sample charts.

A single determination of BMI does not account for variation over time in the amount of body fat or in the rate of growth. Monitoring the rates of gain in weight and height and the relation between them is critical. If a child’s weight increase outpaces height growth, for instance, steps may need to be taken to slow the rate of weight gain. The AAP urges routine assessments of growth by tracking a child’s BMI over time, and strongly encourages using anticipatory guidance about diet, weight, and physical activity in routine clinical practice. Despite these recommendations, a recent report indicated that half of healthcare providers routinely plot BMI and when they did, most reported they did not have time to counsel on weight or obesity and that counseling has poor results (5).

For assessing BMI changes in children, it is important to be aware of the dip in BMI that occurs in early childhood. Children usually thin out after their second birthday; BMI then holds steady for a few years, slowly starting to increase around age six or seven. This upswing from the dip, referred to as the “adiposity rebound,” is now beginning at younger ages, with a high rate of weight gain during the first three years of life. Strong associations have been reported between early toddler weight gain and overweight at age seven (6) and, in African American infants, between rapid weight gain and obesity in young adulthood (7). An extensive review of infant growth studies concluded that infants at the highest end of the weight or BMI distribution or who grew rapidly were at a high risk of subsequent obesity (8). These findings would suggest that caution is needed even before a child begins to walk.

Biological Outcomes

Health in Childhood

Many of the health consequences of obesity seen in adults are now reported in children with high BMIs. The increasing incidence of type 2 diabetes among children parallels the national rise in obesity (9–10). In 2002, in a study of high-risk obese children, 25% were reported to show signs of glucose intolerance, a precursor to type 2 diabetes; this had never been reported previously (11). Most alarming are predictions based on life expectancy data. A child diagnosed with type 2 diabetes at age 10 may lose 17–26 life-years to this chronic disease, a deficit in both quantity and quality of life (12). Numerous other comorbidities have been reported in overweight children and adolescents, including hypertension, metabolic syndrome, hyperlipidemia, asthma, sleep apnea, polycystic ovary syndrome (PCOS), fatty liver disease, orthopedic problems and emotional problems. Overweight children also demonstrate early sexual maturation and increased growth. These health outcomes are discussed below, and treatment of some of these conditions is discussed in Chapter 25 and prevention in Chapters 26 and 27.

Type 2 Diabetes

In the early 1990s, US pediatric endocrinologists began recognizing in children a type of diabetes similar to that seen in adults, type 2 diabetes, although it had been reported in obese Native American children as early as the 1970s. Since then, the global recognition and reports of this condition have increased significantly. In some diabetes centers, it now accounts for about 33–50% of all new cases of diabetes in people younger than 18 years of age; in the mid-1990s it accounted for less than 3% (9). The CDC estimates that, of all children born in the US in 2000, one third to one half will develop type 2 diabetes. Similar studies in Asia and Europe revealed a similar pattern, and in Japan, 80% of all new cases of diabetes in children are diagnosed as type 2 (13).

Most youths affected by diabetes are overweight, have signs of insulin resistance, and belong to certain ethnic minorities, such as Native American, African American, or Mexican American, although obese adolescents of any ethnic group may be predisposed (14, 15). There is also a high incidence in the families of youths with this disorder. Type 2 diabetes is the most prevalent form of diabetes, accounting for 90% of diabetic cases diagnosed in adults. It results from insulin resistance, with an insulin secretory defect within the pancreatic islet B-cell that produces insulin. Insulin helps move glucose from the blood into the cells of the body; glucose is the first choice of energy for these cells. High insulin levels indicate that the body is “resisting” the insulin that is being produced. As a result, the pancreas produces even more insulin, until finally it cannot produce the amount of insulin needed, resulting in elevated blood sugar, or hyperglycemia.

The peak incidence of type 2 diabetes in youth occurs at 13–14 years of age (i.e., at puberty). During this period, insulin resistance normally increases by 30%, thus making overweight youth more vulnerable. According to the American Diabetes Association (ADA), the diagnosis of diabetes in youth is made when either a random blood sugar level greater than 200 mg/dL or a fasting blood sugar level more than 125 mg/dL is observed. The signs and symptoms of diabetes include frequent urination, excessive thirst, excessive appetite, and weight loss, or lack of weight gain despite increased food intake. However, many of those affected do not have any signs or symptoms, and as many as one third of cases are first discovered during a routine exam. A diagnosis of pre-diabetes or impaired glucose tolerance (IGT) is made when the fasting blood sugar is more than 100 mg/dL, but less than 125 mg/dL, or when the two-hour postprandial blood sugar level is more than 140 mg/dL, but less than 200 mg/dL, after an oral glucose challenge (16).

Many adults already have serious complications when diagnosed. It is estimated that there are several million individuals who have type 2 diabetes and even more who have pre-diabetes and do not know it. If pediatric type 2 diabetes mirrors the adult experience, many affected youth also go undiagnosed. In a 2002 study of adolescents of various ethnicities, silent type 2 diabetes was identified in 4% of the obese (11).

Acanthosis Nigricans

Acanthosis nigricans is a skin condition associated with obesity and with elevated insulin levels (insulin resistance). It is seen in up to 90% of youths with type 2 diabetes (9, 17). Acanthosis nigricans presents as a raised brown or gray, velvety, hyperpigmented area of the skin (dermal hyperplasia), found most frequently at the rear base of the neck, in the armpit, in the antecubital areas (in front of the elbow), over joints, and at the beltline; frequently skin tags are associated with it. These markings can help identify persons who run the risk of developing diabetes and other associated conditions, such as polycystic ovary syndrome and the metabolic syndrome. Increased circulating insulin may also raise blood pressure and cholesterol levels (18).

The Metabolic Syndrome

The definition of the metabolic syndrome is controversial in both adults and children; as yet there is no consensus about the criteria to use for children. The metabolic syndrome is a constellation of risk factors generally including large waist circumference, elevated blood pressure, high triglycerides, low HDL-cholesterol concentrations, and high blood sugar levels (19–20). The lipid profile associated with the metabolic syndrome, which places individuals at high risk of cardiovascular disease, consists of hypertriglyceridemia, reduced high-density lipoprotein cholesterol (HDL), and elevated levels of low-density lipoprotein (LDL) particles.

Epidemiologic data from NHANES 1999–2004 (21) and from Weiss and colleagues (22) show that in the US 6.4% of all adolescents, 32% of those obese, and up to 50% of those who are morbidly obese have the metabolic syndrome (1, 22). Obesity plays a central role in the development of the metabolic syndrome. In a recent study, waist circumference was found to be a better predictor of insulin resistance than was BMI; this is likely to be so because waist circumference is associated strongly with the amount of visceral fat, measured by abdominal computed tomography. This fat depot is thought to be more metabolically active than are other depots. The researchers suggested that pediatricians would benefit from including waist circumference, in addition to BMI, in their evaluation of overweight children (23). Researchers are actively working toward the development of standards for waist circumference in children, but currently standards are not available and because children are growing, there are unique challenges to the development of such standards. Children with risk factors associated with the metabolic syndrome are likely to continue to have the metabolic syndrome in adulthood (22).

Cardiovascular Disease: Hypertension, Left Ventricular Hypertrophy, and Atherosclerosis

Studies involving overweight children and cardiovascular risk are limited. However, of concern is that high blood pressure is one of the major risk factors in adults for the development of heart attacks and stroke (24). National, epidemiological studies have suggested that children and adolescents today have higher blood pressure than their counterparts in past decades. One such study (25) found that a higher BMI was associated with higher blood pressure in all age groups; 7.2% of their sample had elevated blood pressure. The prevalence of elevated blood pressure in children increases with increasing age and BMI (25). As children on average have become more overweight, their average blood pressure has increased. There are blood pressure tables for children and adolescents, produced by the National Heart, Lung and Blood Institute, which are based on height percentiles, and include blood pressure data from the 1999–2000 NHANES. For children, hypertension is defined as having a blood pressure greater than the 95th percentile for height, sex, and age (26). When measuring blood pressure in overweight children, it is important to use the right size cuff to avoid an incorrect result.

As with high blood pressure, left ventricular hypertrophy has been linked with increased BMI in children and adolescents (18). The Bogalusa Heart Study indicated that increased insulin and glucose levels in heavier children and adolescents might be a risk factor for increased left ventricular mass, corrected for growth (27).

The most concerning process for developing cardiovascular disease is hardening of the arteries, or arteriosclerosis. In a 1999 study, increased weight during childhood and a high BMI in young adulthood were linked with increased risk of coronary artery calcium deposits in young adults (28). The current generation is at increased risk of developing cardiovascular disease at a young age because these processes may be starting earlier than they previously did, and becoming overweight in childhood seems to accelerate them (18).

Polycystic Ovary Syndrome (PCOS)

PCOS is one of the most common female hormonal disorders, affecting an estimated 5–10% of women of reproductive age, or approximately 6–9 million women in the US, although the prevalence in adolescents is not known. The underlying cause remains uncertain, but it is thought to be multifactorial, involving a variable combination of ovarian and adrenal hyperandrogenism, insulin resistance, obesity, and alterations in gonadotropin secretion (29). Studies have shown that insulin resistance plays a central role in the pathogenesis of PCOS, that both lean and obese women with PCOS are at increased risk for type 2 diabetes and heart disease compared to the general population, and that PCOS can start at a young age. Many researchers think that PCOS may be one of the most serious and prevalent general health concerns of young women. The list of metabolic complications associated with PCOS is quite long and significant. PCOS is the most common cause of female infertility and early (first trimester) miscarriage (30).

The definition of PCOS has been controversial; according to the 2003 Rotterdam criteria, patients must have at least two of the following three conditions to make the diagnosis: 1) oligomenorrhea (eight or fewer menses per year) or anovulation; 2) clinical manifestations of androgen excess and/or elevated levels of circulatory androgens (i.e., total or free testosterone); 3) polycystic ovaries on ultrasound evaluation, after ruling out other etiologies. Typical complaints of patients are irregular menses, hirsutism (excessive hair growth), acanthosis nigricans, resistant acne, alopecia (male pattern baldness), weight gain, and/or trouble losing weight. The signs and symptoms of PCOS usually appear during or close to the onset of puberty. Signs of precocious pubarche (PP, i.e., early pubic hair development, axillary hair, or apocrine odor in girls < 8 years) may be an early marker of future PCOS. Up to 45% of these girls have been shown to develop adolescent hyperandrogenism with or without insulin resistance (31, 32). Retrospective studies on PCOS patients have suggested the existence of specific prenatal risk factors for the post-pubertal expression of the PCOS phenotype, such as high birth weight, low birth weight, and maternal obesity (31, 32), presumably because prenatal overgrowth or growth restraint is associated with a degree of insulin resistance and abdominal fat excess, especially when postnatal weight gain has been excessive. Ibanez (31) showed that prepubertal therapy with insulin sensitizers (metformin) had normalizing effects on PCOS features (decreased insulin and androgens) in high-risk girls with low birth weights and PP, and it disrupted the progression from PP to PCOS. These young girls’ lipid profiles also improved, with an increase in HDL and a decrease of LDL cholesterol levels. Once metformin therapy was discontinued, renewed progression of PCOS features was seen within six months (32).

Although obesity is not considered the cause of PCOS, it is found in approximately 70–90% of patients. Being obese seems to set the stage for developing the associated metabolic derangements, including insulin resistance. In adolescent girls and young women, excess central or abdominal body fat is associated with hyperandrogenism and strongly correlates with insulin resistance (33–34). Insulin resistance stimulates ovarian as well as adrenal androgen and estrogen production. It is believed that both an intrinsic insulin resistance (35) and ovarian hypersensitivity to insulin (36) are involved. It has been shown that medications that decrease insulin resistance often attenuate the hyperandrogenism and metabolic abnormalities present in both obese and lean women.

Adult women with PCOS have a combined prevalence of impaired glucose tolerance or type 2 diabetes of 30–40%, but even more disturbing, these can develop at an early age, and a substantial proportion of IGT in adolescent girls is associated with PCOS (11, 29, 37). In adolescents with previously diagnosed PCOS, 4% had type 2 diabetes and 30% had IGT. In women with PCOS, the 2–hour plasma glucose level after an oral glucose tolerance test (OGTT) was the most reliable screening test, better than a fasting glucose (29, 38). A 2005 study (39) found a conversion rate from IGT to type 2 diabetes of 2% per year, but a dramatic increase, 16% per year, was seen in the conversion rate from normal glucose tolerance to IGT. The authors concluded that women with PCOS should routinely have an OGTT, especially if they are overweight and have a family history of type 2 diabetes (39).

By age 30 years, 30–35% of obese women with PCOS will develop type 2 diabetes or IGT, the prevalence of which is 10-fold higher than in an age-matched population. These young women are also at risk of developing cardiovascular disease, although long-term outcome studies for women with PCOS are not yet available. Dyslipidemia with low levels of HDL, high LDL, and high triglyceride levels are found in up to 70% of women with PCOS. They also have increased markers for early atherosclerosis such as PAI-1, endothelin-1, and C-reactive protein concentrations in the blood. By age 20–29 years, 45% of women with PCOS were found to have the metabolic syndrome (30). Recent studies have begun to show similar abnormalities in young girls with PP and PCOS (31, 37).

Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease is increasingly observed in children; it is strongly associated with obesity and insulin resistance. It is currently considered by many as the hepatic component of the metabolic syndrome. The estimated prevalence in the pediatric population is 3–8% overall, but it is seen in up to 50% of obese patients (18). NAFLD ranges from steatosis, which is simple, fatty liver, to nonalcoholic steatohepatitis (NASH), which is fatty liver with inflammation and/or fibrosis, to advanced fibrosis and cirrhosis. The diagnosis is similar in children and adults, made during further evaluation for elevated aminotransferases in blood. NAFLD also may be identified on ultrasound or liver biopsy.

Respiratory Problems: Sleep Apnea and Asthma

There is a strong relation between obesity and obstructive sleep apnea (OSA) in both adults and children. Obese children are 4–6 times more likely to have OSA than their lean counterparts (40). Sleep apnea may be one of the most important and under-recognized medical complications in overweight children and adolescents. In OSA there is an abnormal collapse of the airway during sleep, resulting in snoring, irregular breathing, and disrupted sleep patterns. Those affected are usually very sleepy during the day, which decreases physical activity and promotes obesity. Daytime sleepiness may harm school performance. Untreated OSA can lead to increased blood pressure in the pulmonary artery and decreased blood flow to the heart due to low oxygen levels in the blood. Over the long term, this can lead to hypertension and increased ventricular mass and eventual cardiac dysfunction (40).

Rodriguez and colleagues found that children with a BMI above the 85th percentile had an increased risk of asthma, independent of age, sex, ethnicity, socioeconomic status, and exposure to tobacco smoke (41). It is still unclear whether obesity contributes to asthma, or whether having asthma increases one’s risk of obesity due to decreased activity or medications used to treat the asthma, such as corticosteroids, which promote a pattern of increased visceral fat accumulation. Studies in adults with asthma have shown that weight loss can improve pulmonary function (42). Obesity may have a direct effect on the mechanical behavior of the respiratory system, as excess abdominal fat can alter lung function by decreasing compliance or elastic recoil, resulting in reduced effective lung volume, airway diameter, or respiratory muscle strength (43).

Orthopedic Problems

Overweight children are at increased risk of developing bone deformities that can predispose them to other orthopedic problems later in life. Excess weight can cause injury to the growth plate and result in an increased incidence of slipped capital femoral epiphysis (hip dislocation) and Blount’s disease (bowing of the legs). Both are more commonly seen in males, and slipped capital femoral epiphysis is seen more often in African Americans. The excess weight on the joints results in wear and erosion of weight-bearing joints. This increases the risk of osteoarthritis of weight-bearing bones, and can also cause flat kneecap pressure/pain, flatfoot, spondylolisthesis (low back pain), and scoliosis (44). Studies that followed obese teenage girls for 25 years found that “weight wears out the hips”; they were three times more likely than healthy-weight women to need a hip replacement later in life (45).

Lower Quantity and Quality of Life Than in the Parents’ Generation

The most concerning aspect of childhood and adolescent obesity is its potential to persist and result in more severe overweight in adulthood. Reports suggest that about a third of obese preschool children and about half of obese school-age children become obese adults. If obesity continues into adolescence, there is more than a 70% chance of its persisting into adulthood (46). Thus, childhood obesity may predict a multitude of serious health problems in adulthood. The National Institutes of Health estimates that, in a few years, Americans will have a five years shorter national average lifespan if we do not curb obesity, especially in our young. The worst prediction is that this generation of children could be the first to have a shorter life expectancy than their parents’ generation (47). It has been estimated that the obesity epidemic in children is already costing the US healthcare system $14.1 billion a year (48). In addition, it has been noted (49) that overweight in adolescence predicted a broad range of adverse health effects independent of adult weight after 55 years of follow-up. Van Dam and colleagues (50) reported that an elevated BMI at age 18 years, based on recalled weight, was associated with increased premature death in women enrolled in the Nurses’ Health Study II. Therefore, greater efforts need to be made to understand more clearly the etiologies of continued weight gain and to prevent it.

Social Outcomes

Social Stigma

In addition to its physical consequences, childhood overweight often results in significant emotional difficulties. Obese children tend to be taller and have advanced skeletal growth. Some may even have advanced puberty, with reported menarche in 10-year-old girls (33). Since they are taller, they are expected by some adults to behave as if they are older, and this may add undue stress on overweight children. Children are likely to ridicule and exclude their overweight peers, contributing to their poor body image and low self-esteem. Data from the large, comprehensive, and highly representative National Longitudinal Study of Adolescent Health indicate that overweight adolescents receive significantly fewer friendship nominations from other adolescents compared to normal-weight peers. Overweight adolescents are isolated and peripheral to social networks compared to normal-weight adolescents (51). Perceiving themselves as fat, having negative feelings about their appearance, or believing their parents have negative feelings about their size can result from body-size stigmatization (52). Most experts agree that this stigmatization originates in the child’s social and cultural surroundings, rather than being a normal part of cognitive development (53, 54).

A report comparing a classic 1961 study and its replication 40 years later illuminates how victimization of overweight children has not abated. The study report title tells the tale: Getting Worse: The Stigmatization of Obese Children (55). When this study was dramatized in a 1995 television documentary called Fat, one reviewer noted, “Five-year-olds still prefer to lose an arm than be fat” (56). Young children of all body types were shown six pictures of children—four with various physical disabilities or disfigurements, one overweight, and one a healthy weight—and were asked to choose, in order of preference, a friend. The fat child was nearly always chosen last, significantly more so in 2001 than 1961. Children rate overweight peers as less liked and less preferred as friends or playmates than normal-weight peers or peers with handicaps.

Very young children also demonstrate strong stigmatization toward overweight peers. In response to stories about “mean” versus “nice” actions by children, 3–5-year-olds unanimously chose pictures of overweight children as “mean” and thin children as “nice.” Among these preschool children, the cultural stereotype that “fat is bad” was pervasive regardless of the child’s own body size (53). This topic is covered in more detail in Chapter 2.

Teasing, Isolation, and Fat Discrimination

Families show their stigmatization through teasing, often calling young children “chubs” or “fats.” Eisenberg and colleagues (57) found that among overweight youths, 19% of girls and 16% of boys were teased by family members. Many were teased by both peers and family members (57). A high level of implicit anti-fat bias is observed among health professionals who treat obesity, who associate obese people with “bad” characteristics and thin people with “good” ones, expressing strong stereotypes that fat people are lazy, stupid, and worthless (58). Some pediatricians, especially those perceiving themselves as thin or overweight, report a lack of ease in counseling children and parents about weight (59). A study of dietetics students reported high scores on a “Fat Phobia” scale, similar to non-dietetics students and the general public (60).

To combat this all too accepted form of discrimination, initiatives such as Health-at-Every-Size (HAES) focus on promoting healthy eating and movement, regardless of size. Evidence that this approach, compared to a traditional weight loss program, reduces some risk factors among women without weight change suggests that adults may benefit from HAES, especially in weight maintenance (61). With fat children, social stigmatization and its effects appear strong and, as yet, unchanged.

An immoderate, intolerant “Food Police” attitude on the part of parents or health providers typically makes its victims miserable and promotes a vicious cycle. Having unattainable expectations encourages peer tormentors and discourages a child’s own best efforts. More disturbing are the serious side effects that can result from negative feedback. In addition to encouraging further weight gain, these approaches increase five-fold the likelihood of an overweight child having an impaired health-related quality of life compared to a healthy-weight child—about the same as in children with cancer (62). Other studies indicate that being teased about body weight is consistently associated with depression and thoughts of suicide (63–64).

Cognitive and Psychological Outcomes

Academic Performance

Childhood overweight is linked directly to low academic performance in boys and to behavior problems in girls, according to data from the ongoing US Department of Education’s Early Childhood Longitudinal Study of children as they enter school. Overweight boys’ math scores were significantly lower than those of other boys, even with parental education controlled (65). In girls, there was a strong association between overweight and behavior problems, such as anxiety, loneliness, low self-esteem, sadness, anger, arguing, and fighting (66). These relationships are important because, in both obesity and mental health conditions, symptoms occur along a spectrum. An overweight child may be doing poorly in school owing to depression, or may have difficulty learning because of daytime sleepiness from OSA, or as a result of emotional distress caused by teasing from peers (67).

Obesity-Related Eating Disorders

Restrictive, calorie-deficient diets, and those described in popular magazines and books, can be unhealthful and harmful. In fact, dieting can be an important predictor of new eating disorders in adolescent females. Adolescents from diverse ethnic and socioeconomic backgrounds were followed over five years in the Eating Among Teens (EAT) study (68). At baseline, 57% of the girls and 25% of the boys reported dieting or unhealthful weight-control behaviors (fasting, eating “little” food, using food substitutes such as powders and liquids, or skipping meals). Five years later, about one fourth of the girls and boys were overweight; three times more girls than boys reported binge-eating and extreme weight control behaviors (using diet pills, laxatives, vomiting). Girls using dieting or other weight-control behaviors were three times more likely to be overweight than those who did not diet or use these methods (68). This study also explored why dieting predicts weight gain over time in adolescents. Reported behavioral patterns that did not support healthy weight management were binge-eating and skipping breakfast, in both female and male adolescents, and decreased physical activity in males (69).

Many researchers have explored dieting as related to weight and health among adolescents and young children. What does “dieting” mean to preteens and teens? Is it positive or negative? Is it another word for healthy eating? Does mention of body weight by health providers or parents propel vulnerable teens toward eating disorders? Obsessive dieting, like obesity, may be an epidemic among teens. Nearly 60% of girls and 30% of boys in federal nationwide surveys report being on a diet (70). In linking body size to a body size standard, some girls in the Teen Lifestyle Project said that dieting meant “watching what they ate,” or healthy eating. The majority, however, described dieting as restrictive, marked by “being good or bad,” depending on whether they were “sticking to a plan” or “blowing it.” Black girls were less rigid in their diets and their concepts of beauty than White girls and spoke positively about having a larger body and “making what you’ve got work for you” (71). A study of 700 teenage girls conducted over four years found that girls with a normal weight who dieted in ninth grade were more than three times as likely to be overweight in twelfth grade, as compared with girls who did not diet (72). Tracking dieting behavior of 15,000 girls and boys, The Growing Up Today Study (GUTS) reported that teens who dieted were more likely to gain weight than non-dieters, and were also much more likely to binge eat than non-dieters (73). Among 6–12-year-olds at high risk for adult obesity followed for over four years, both binge-eating and dieting predicted increases in body fat. Those who self-reported binge-eating had an average 15% more body fat mass compared with children who did not report binge-eating. Both binge-eating and dieting were reported as important predictors of gains in fat mass during middle school (74).

When asked whether health professionals providing nutrition-related information should emphasize weight control or health, girls were concerned that overemphasizing weight control might lead to unhealthful weight preoccupation. The investigators suggest that girls would benefit from discussions about paying attention to internal signs of hunger and satiety, and to portion size and healthy food choices, rather than discussion about weight (75). In general, focusing children of all weights on healthful eating and maintenance of physical activity will likely be an important approach for improving the health and development of all children. It is important to recognize that excess weight has adverse effects on all aspects of life, including the physical, social, and mental health of children and teens. Thus, it is critical to address the problem of obesity by both prevention and treatment. In addressing the issue of weight, the professional must be sensitive to the difficulties faced by the child and the family and support any change that will enhance overall health.