Multiple: Childhood Obesity
Multiple: Childhood Obesity
Childhood obesity is a condition that develops when children or teenagers take in more food calories than their bodies burn up. The most common assessment of obesity is made by calculating an individual's body mass index (BMI). Although obesity in adults is measured by the body mass index (BMI), which does not take age and sex into account, the Centers for Disease Control and Prevention (CDC) measure overweight and obesity in children and adolescents by percentiles of BMI.
The CDC has compiled growth charts on the basis of BMI for boys and girls at specific ages. The percentile indicates the relative position of the child's BMI number among children of the same sex and age. In screening children for overweight or obesity, the 85th percentile is regarded as an indicator that a child is “at risk” for overweight. A BMI above the 95th percentile is defined as “overweight.” The American Obesity Association (AOA) uses the CDC's 95th percentile cutoff as the definition of “obesity,” not just “overweight.” There are also some researchers who define obesity in children as body weight at least 20 percent higher than a healthy weight for a child of that height, or a body fat percentage above 25 percent in boys or above 32 percent in girls. A child's primary care doctor may use any or all of these standards for evaluating whether an overweight child is obese.
Childhood obesity, once a rare condition, has become a major public health concern in the United States and other developed countries. It is a serious health problem not only because it virtually guarantees a lifelong struggle with weight when the young person reaches adulthood but also because it leads directly to diseases and disorders once seen only in adults, including asthma, type 2 diabetes, skin rashes, high blood pressure, liver disorders, and high blood cholesterol levels. In addition to physical problems, obese children are also at risk of depression and other psychological problems related to teasing and criticism of their appearance. Depression in turn can lead to difficulties in school and lifelong underachievement.
The percentage of overweight and obese children in North America has tripled since the mid-1970s. In 1976 the percentage of children (defined as youngsters between the ages of six and eleven) defined as obese was 7 percent, and the percentage of obese adolescents (ages twelve to nineteen) was 5 percent. By 1988 11 percent of young people in both age groups were obese, and by 2000 the percentages were 15.3 percent for
children and 15.5 percent for adolescents. Those figures mean that one American child in every six is obese.
Childhood obesity appears to be more common in girls than in boys, but is more obvious in boys because fat in boys tends to accumulate on the chest and stomach rather than being more widely distributed to other parts of the body.
Childhood obesity is more common in African American, Hispanic, and Native American children than in Asian or Caucasian children. It is also more common in children from families with lower family incomes.
Genetics is one factor influencing childhood obesity that cannot be changed. Having at least one parent who is obese increases a child's risk of obesity throughout life. Researchers disagree, however, on the importance of genetics as a factor in obesity. Some doctors have pointed out that the rapid rise in the rate of childhood obesity within three decades could not be caused by genetic factors alone. One study reported that 41.95 percent of the children in the study with normal-weight mothers were obese or overweight while 34.25 percent of children with normal-weight fathers were obese or overweight. Most doctors in the early 2000s regard childhood obesity as the result of a combination of genetic factors and behaviors (food choices, exercise, and eating habits).
A small percentage of overweight children (less than 10 percent) become obese because of metabolic or genetic disorders. These disorders include Cushing syndrome, caused by a tumor in the pituitary gland; Turner syndrome; achondroplasia (dwarfism); disorders of the thyroid gland; and Prader-Willi syndrome, a rare genetic disorder characterized by mental retardation and an abnormally large appetite for food. In a few cases children become obese as a side effect of medications given to treat rheumatoid arthritis and a few other diseases.
Most doctors believe that the most important factors in childhood obesity are:
- Poor food choices. The easy availability of fast foods and junk foods, combined with parents' allowing children to choose their own foods at home instead of eating shared meals with the family, is one reason why many children become obese.
- Lack of exercise. The popularity of computers, video games, and television as leisure-time activities means that the average child is now much less active than a child in the 1970s. Many children spend as much as four hours a day watching television. Researchers studying a group of 133 children in a suburban community discovered that the obese children were 35 percent less active on school days and 65 percent less active on weekends compared to children of normal weight.
- Psychological factors. Some children learn to use food to calm or comfort themselves when they feel lonely or anxious, in some cases by watching their parents eating when they feel stressed. Unfortunately, stress-related eating sets up a vicious circle in which the child's weight gain often leads to further loneliness or greater anxiety, and more eating.
- Sleep deprivation. Children who do not get enough sleep do poorly in school, which in turn can lead to low self-esteem and overeating.
- Social factors. Get-togethers and other family or group activities centered on food (holiday meals and parties, etc.); advertisements in the mass media that encourage overeating or poor food choices; and schools that have cut back on physical education programs.
- Economic factors. Low family income and obesity are often associated because low-income parents may lack the time and resources to make healthful eating habits and exercise a family priority.
The diagnosis of childhood obesity may be based on the CDC body mass index tables for children and adolescents or on other measurements. One common test involves measuring the thickness of the skin fold over the triceps muscle on the upper arm, although this measurement may not be accurate unless performed by a trained technician. Another test involves measuring the child's waist circumference at its widest point, usually at or just below the belly button. If the waist measurement is above the 90thpercentilefor thechild's age and sex, the child is at increased risk of type 2 diabetes and the health complications that accompany it.
Treatment of childhood obesity is broad-based and involves the whole family, not just the affected child or teenager. The child's pediatrician can help draw up a treatment plan. Most plans include the following:
- A reasonable weight loss goal for the child, no more than 1–4 pounds (0.5–1.8 kilograms) per month. An overly ambitious goal is likely to lead to failure and making the child discouraged.
- A dietary prescription from the doctor that specifies the total number of calories per day and recommended percentages of calories from fat, protein, and carbohydrates.
- Increasing the child's level of physical activity to twenty to thirty minutes per day in addition to school sports or other physical education activities.
- Nutrition education. This part of treatment usually involves asking the child to keep a food diary and monitor his or her daily food intake as well as learning about what makes a healthful diet and how the body uses food.
- Family involvement. This may involve nutrition counseling for the parents as well as advising them about substituting family outings focused on physical activity rather than television viewing. Several studies have shown that weight management programs involving the entire family are more successful than those aimed only at the overweight child.
The likelihood that an obese child will grow into an obese adult depends on three major factors: the age at which the child became obese; the severity of the obesity; and the presence of obesity in at least one parent. Overweight in a child under three years of age does not mean that the child will necessarily be obese in adult life unless at least one parent is also obese. After age three, however, the likelihood that obesity will persist into adulthood increases with the age of the child and is higher in children of any age who are severely obese. After an obese child reaches six years of age, the probability that obesity will persist into adult life is greater than 50 percent; moreover, 70 to 80 percent of obese adolescents will remain obese as adults. The presence of
obesity in at least one parent increases the risk of obesity in adult life for children at every age.
Obese children have a poor prognosis for good health in adult life. They are at increased risk for a number of serious long-term health problems, including type 2 diabetes, hypertension (high blood pressure), osteoarthritis, heart attack, stroke, and damage to the eyes, heart, and kidneys.
Prevention of childhood obesity is increasingly important. The American Academy of Pediatrics (AAP) makes the following recommendations for parents:
- If possible, breast-feed children rather than bottle feeding them.
- Respect a child's appetite; do not insist that the child finish every feeding or meal.
- Limit the high-calorie and sugary foods kept in the house.
- Provide a nutritious diet with ample fiber from fruits and vegetables, with no more than 30 percent of calories derived from fat.
- Do not use food as a reward or bribe a child to finish a meal by offering sweets.
- Limit the child's television viewing or video games to no more than two hours per day.
- Encourage the child to participate in sports and other activities involving physical exercise (nature walks, dancing classes, hiking, etc.)
- Plan family activities around outdoor walks, bicycling trips, etc.
The CDC expects the percentages of obesity in children and teenagers to continue to rise over the next few decades, as it is unlikely that there will be large-scale changes in people's eating habits and food choices. In addition, it is unlikely that the next few years will see any major breakthroughs in the treatment of obesity in adults.
SEE ALSO Achondroplasia; Anorexia; Asthma; Bulimia; Diabetes; Hypertension; Sleep apnea
WORDS TO KNOW
Body mass index: An indirect measurement of the amount of body fat. The BMI of adults is calculated in English measurements by multiplying a person's weight in pounds by 703.1, and dividing that number by the person's height in inches squared.
Pituitary gland : A pea-sized gland located at the base of the brain behind the nose that secretes growth hormone and other hormones that affect sexual development and the body's response to stress.
Hassink, Sandra J., ed. A Parent's Guide to Childhood Obesity: A Roadmap to Health. Elk Grove Village, IL: American Academy of Pediatrics, 2006.
Thompson, Colleen, and Ellen Shanley. Overcoming Childhood Obesity. Boulder, CO: Bull Publishing Co., 2006.
Torgan, Carol. “Childhood Obesity on the Rise.” Word on Health, June 2002. Available online at http://www.nih.gov/news/WordonHealth/jun2002/childhoodobesity.htm (accessed May 2, 2008). Word on Health is a publication of the National Institutes of Health.
American Obesity Association (AOA). Childhood Obesity. Available online at http://obesity1.tempdomainname.com/subs/childhood/ (accessed May 2, 2008).
Centers for Disease Control and Prevention (CDC). Childhood Overweight. Available online at http://www.cdc.gov/nccdphp/dnpa/obesity/childhood/index.htm (accessed May 3, 2008).
Mayo Clinic. Childhood Obesity. Available online at http://www.mayoclinic.com/health/childhood-obesity/DS00698 (updated March 28, 2008; accessed May 2, 2008).
National Center for Health Statistics (NCHS). 2000 CDC Growth Charts: United States. Available online at http://www.cdc.gov/growthcharts/ (updated March 7, 2008; accessed May 3, 2008). This is a link to the CDC's growth charts for measuring overweight and obesity in children and adolescents.
NOVA Science Now. Obesity. Available online at http://www.pbs.org/wgbh/nova/sciencenow/3313/03.html (aired October 3, 2006; accessed May 2, 2008). This is a twelve-minute video on the genetic factors involved in obesity; available in several formats.