The prevalence of obesity is increasing in children and adolescents throughout the world.1 The increased number of obese children has been demonstrated in British children studied at 24. 49, and 61 months and cross-sectional decade studies.2,3 It is now estimated that there are more obese than malnourished individuals This global problem is not limited to one age, gender, or ethnic group, although in the United States obesity is more prevalent in certain ethnic groups, such as African-American and Hispanic.1 While twin studies have shown that inherited factors affect our body mass, the rapid increase in obesity over the past 20 years suggests that environmental changes are a more important cause. These changes promote decreased energy use and increased energy input.
Recent surveys indicate that the number of overweight children in the United States has doubled within three decades.4 From the late 1970s to 1999, me prevalence of overweight increased from 7.6% to 13% for children aged 6 to 11 years, and from 5.7% to 14% for children aged 12 to 19 years. The most recent data estimate mat 22% of children are overweight, as defined by a body mass index (BMI) of greater than the 85th percentile (see pediatric growth chart).5 The current prevalence of obese children, defined by BMI greater than the 95th percentile, is 10.9%.
Childhood obesity is a public health crisis. About 80% of obese children become obese adults. If childhood obesity persists into the adult years, morbidity and mortality are worse than if the obesity developed in the adult.6 Many of the cardiovascular and metabolic complications that are commonly associated with adult obesity have their onset in childhood. Childhood obesity is associated with elevated levels of lipoproteins, cholesterol, low-density lipoprotein cholesterol, blood pressure, and insulin in adulthood and this is almost entirely due to the strong tracking of obesity from childhood to adulthood. This, in turn, is associated with increased morbidity from coronary heart disease. Childhood obesity has been called "one of the greatest neglected public health problems of our time with an impact on health which may well prove to be as great as smoking."
FACTORS AFFECTING THE CHILDHOOD AND ADOLESCENT OBESITY EPIDEMIC
Cultural changes over the past three decades involving food intake have also contributed significantly to the increase in childhood obesity. A number of changes are obvious. Dinner is no longer an integral part of American family life. The wife does not shop and cook and serve with help from her children. Neither do most families have dinner sitting together at one time. Eating out, once quite uncommon, has become routine. We are eating out more and eating fast food that is inexpensive and high in calories, fat, and cholesterol. Children who eat meals with their family consume more fruits and vegetables, fewer carbonated drinks, and less fat in food.8 Fast food is marketed on television to children with toys, music, and social icons. Studies have shown that even 30-second exposure to commercials influences preschoolers' food preferences. In 1997 Coke and Pepsi spent in excess of $200 million to advertise their products, while only $1 million was spent by the American Cancer Society to advertise the benefits of eating fruits and vegetables.4 Television advertising of food may help explain the work of Robinson and Dietz suggesting a direct link between television watching and BMI.9,10
Fast food restaurants offer the choice to increase portion sizes by up to 20% for minimal additional cost, adding hundreds of extra calories. Usual portion sizes are already much greater than they were just 10 years ago. Portion sizes in restaurants, take-out foods, and snacks have increased more than 100%. The small soda, for example, is currently 20 ounces rather than the 8 ounces that it was in the 1980s. Twenty-two to thirty-six ounce portions of steak and fish are normal, when only four to six ounces are required per day. Bagels and muffins have doubled in size.
Fast food is now offered in many public schools as an alternative to school lunches. Many schools, especially middle and high schools, offer alternative lunch lines that give children the choice of high fat, high calorie foods such as hamburgers, frencb fries, and pizza instead of the school lunch. It is considered cool for children to eat from the alternative food line and uncool to eat the standard school lunch. Even children receiving free school lunch will spend the money to buy food from the alternative line. However, even the standard school lunches have 6% more fat than the recommended daily allowance. Food is denser in calories, eaten without exercise or work to get it, and made so highly palatable and enjoyable that it may be more logical to think of it as a pleasure of daily life or a drug than as sustenance, necessary for existence. Hedonic eating taught early, persists and becomes typical of today's youth.
The widespread availability of television, computers, and video games has been associated with increased sedentary activity and decreased exercise. Randomized, controlled trials have shown a direct relationship between television viewing behaviors and body fatness.11 Indeed, the number of hours of television viewed per day is a better predictor of being overweight than hours spent in front of computers or video games. The rate of obesity is 8.3 times greater for children who watch more than 5 hours of television per day, compared to those who watch 0 to 2 hours per day.12 Investigators have hypothesized that television directly influences obesity by three mechanisms: (1) displacement of physical activity; (2) increasing caloric consumption, either by passive snacking while watching television or as a result of advertising; and (3) reducing resting metabolism. Television might simply serve as a delivery system for food advertising.13
A reduction in physical activity in modern life is evident. Children do not work the farm or help their parents with manual tasks. Children do not ride their bikes or walk to school as they did in the recent past. There is an increased reliance on technology and labor-saving devices that have resulted in a decline in physical activity.12 Fewer than one third of elementary school children have daily physical education and fewer than one fifth have extracurricular physical activity programs at their schools.14 This is important, as 60% of physically active adults state that they were encouraged to remain active later in life by physical education classes in middle and high school. The Oslo youth study followed children for 1 2 years, and found that early physical activity levels were predictors of activity levels in adulthood.15 Even in communities where opportunities exist for extracurricular activities many children are excluded. Often the child who needs the exercise the most is the one who is excluded.
Parents and children have a poor understanding of how much exercise children are actually getting each day, and how much exercise is appropriate. Sixty-eight percent of parents are satisfied with the amount of exercise that their children are getting from school physical education programs. However, 59% percent of those parents report that their children spend less than 2 hours per week involved in physical activity.16 Children markedly overestimate the amount of exercise that they are getting each day. Forty-five 11-year-old to 13-year-old children wore electronic activity monitors for two 4-day periods, and were asked to estimate the time that they spent in moderate or vigorous activity. They thought that they spent 3.2 hours per day in activities, when the monitor estimated that they spent 0.9 hours per day. The children thought that they spent more man an hour each day in vigorous activity, when they actually spent only 2 minutes per day in such activity.16 Both parents and children would think that they could eat more and be calorie neutral because of failures in calculating what exercise was actually done and what was imagined.
Aerobic exercise works to reduce fat, increase self-esteem, and empower children or adolescents to control their body mass. Even a moderate amount of aerobic exercise for 6 monms, without dietary restriction, produces a significant loss of magnetic resonance imagingraeasured fat in women.17
The gene pool has not changed from the 1980s to the present. Hence, the epidemic in obesity cannot be attributed to genes. Familial prevalence of obesity suggests a genetic predisposition to being overweight. Obese children usually have a family history of obesity, especially in their mothers.18 In addition, identical twins have similar weights even if reared apart.19 Twin studies also show a heritability of distribution of fat mass, with 30% of the variance in fat distribution being accounted for by genetic factors and disorders of energy balance.20 A study of children whose parents have type 2 diabetes mellitus, which is associated with obesity, showed that children who were at risk for being overweight had a lower resting energy expenditure than their peers with normal weight parents, when matched for age and body mass index.21
Genetic studies have shown that there is a continuum between different forms of human obesity.22 There are rare cases, mainly very severe forms of obesity beginning in early childhood, that are single gene conditions transmitted by a recessive inheritance, in which the environment simply plays a permissive role.23 Over the past 3 years there has been identification of some genetic defects responsible for different monogenic forms of obesity; the leptin, leptin receptor, pro-opiomelanocortin, prohormone convertase- 1, melanocortin-4 receptor, and gherlin genes have all been implicated.24 The most common forms of obesity, however, are polygenic, and as of yet, specific genetic defects cannot be identified.25
Obesity that starts in childhood has many consequences, both physical and psychological. Type 2 diabetes, previously unheard of in children and adolescents, now accounts for 30% of new cases. Most cases of type 2 diabetes are attributable to obesity.26 Acute physical problems include orthopedic abnormalities such as slipped capital femoral epiphyses and Blount disease with bowing of the legs and tibial torsion, pseudotumor cerebri, sleep apnea, gallstones, and steatohepatitis (fatty liver). Obesity is also associated with insulin resistance which, in turn, results in the dysmetabolic syndrome (Syndrome X) and increased long-term morbidity. This syndrome is defined as hypertension, elevations in lipids, elevations in plasminogen activator- 1 , evidence of hyperandrogenism, and type 2 diabetes mellitus. The hyperandrogenism usually presents as polycystic ovary syndrome and is associated with hirsutism, acanthosis nigricans, and menstrual irregularities. Another long-term consequence of childhood obesity is proteinuria, which can result in endstage renal disease.27 The proteinuria is associated with hypertension, specifically elevations in systolic blood pressure, which is seen in many obese individuals. The hypertension, increased plasminogen activator- 1, cholesterol, low density lipoprotein cholesterol and triglycerides contribute to the development of cardiovascular disease. Obese children are 9 to 10 times more likely to have high blood pressure as adults than non-obese children; this blood pressure elevation may start as early as 5 years of age.6 The Bogalusa Heart Study showed that plaques and fatty streaks are already starting to develop in the arteries of obese children.6 Atherosclerosis, colon cancer, and arthritis are additional problems that can arise in adulthood secondary to childhood obesity. The relative risk of mortality in adulthood is increased 1 .5 to 2 times in those individuals who had childhood obesity.27 The rising prevalence of obesity with its resulting morbidity and mortality is causing an ever-expanding burden on our health care system.
The social and psychological impact of obesity can be significant. Children as young as 5 years ascribe negative terms, like lazy and ugly, to obese peers.28 Preschool children demonstrated prejudice toward fat toy figurines as compared to normal figures.29 These attitudes are likely to affect body image and self-esteem of overweight children. Lower self-concept has been reported in overweight children as young as 5 years.30 Depression and anxiety disorders become more common among young women as body weight increases. Obese women have high rates of anxiety disorders, affective disorders, somatoform disorders and child psychiatric disorders from separation anxiety to disruptive behavior.30 Child psychiatrists should evaluate and treat obese children and adolescents not only with psychotherapy and psychotropic medications, but also with weight management. The diagnosis of major depression by DSM-IV has many somatic items that are endorsed by obese adolescents but are clearly due to body mass. Weight loss is often an antidepressant when a Beck Depression Inventory is done before and after a successful program. Sleep changes, sexual function changes, body image, interest changes, and so on are part of the natural history of obesity and necessary for a psychiatric diagnosis of depression.
Louis Pasteur said, "When meditating about a disease, I never think of finding a remedy for it but rather a means of preventing it." The overwhelming negative consequences of obesity mandate that prevention should be a primary goal of every physician who sees children, beginning with parental education early in the child's life. Promoting breast feeding, starting regular family sit-down meals, and reducing number of snacks will help. Parents should take responsibility for what children are offered to eat and whemer it is advisable for them to eat it. Prevention of obesity is easier than treatment. However, children with a BMI of greater than the 95th percentile for age often require weight reduction. The initial approach in treatment of childhood obesity is a comprehensive evaluation for medical, neurological, endocrinologie, and psychiatric illness that might cause weight gain. If the weight gain is not due to another primary illness, encourage patient and family education, behavior modification, and joining a group program that incorporates exercise, nutrition education and motivational enhancement techniques, and reduce access to highly addicting and enjoyable foods.31
Currently, no weight loss medications are approved for use in children. While obesity pharmacotherapies work in adults, they work only for as long as they are consumed. If diet and exercise and psychiatric and lifestyle changes are not also undertaken, mere is rapid weight rebound, usually to a higher weight, after medications are discontinued.
Pediatric obesity has become a problem of epidemic proportions. The problem is becoming worse each year. Overeating, underexercise, and a sedentary lifestyle have created obesity and diabetes epidemics. Health care providers are well aware of the long-term implications of this problem, but are unable to solve it. It will take a team approach. Treatment of obesity, like treatment of addiction, requires changes in daily life and expectations for the entire family. Food cravings play an important role in maintenance of overeating, binge eating, bulimia, and obesity.32 Such intense desire to consume a particular food or type is difficult to resist. You may be powerless over food, eat more than intended, eat the wrong food, but unlike an addiction, food cannot be stopped. However, fast food and highly palatable food can be stopped. Structured exercise programs have been shown to be the most effective tool for weight reduction in obese children.33 Even when children's body weight and adiposity did not change following 50 minutes of aerobic exercise three times per week, blood lipid profiles and blood pressure did improve.34 Sixty percent of overweight children have what appears to be another cardiovascular disease risk factor as well. It is vital to the health of our children that this problem be recognized and addressed as early in childhood as possible, and treatment for the whole child initiated.
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