Risk Factors for Obesity

Obesity in Children: Special Considerations

Obesity in children and adolescents is rising at an alarming rate. Currently over 15% of young people over 6 years old are obese, and obesity is also increasing children age 5 and younger.

Definition of Obesity in Children

Children are considered to be overweight if the BMI is over 85% of the weight group in their age and sex categories. If it is 95% and over, they are considered to be obese. Adolescents are generally judged according to adult criteria for obesity, although there are other considerations in this population. Ethnic variations, timing of growth spurts, and higher normal fat levels around puberty can cause disparities in these measurements.

Causes and Risk Factors for Obesity in Children

Lifestyle Factors. Without educational or parental guidance, children are extremely vulnerable to the intense cultural pressures that are largely responsible for the obesity epidemic. The following are some specific problems created by the culture:

• Excessive television watching plays a critical role in obesity in children. Not only is it a sedentary activity, but television also offers innumerable temptations with its advertisements for fast foods, sugar cereals, and unhealthy snacks. In one study obesity rates were lowest in children who watched television one hour or less a day and highest in those who watched four or more hours.
• Sugar, particularly from soda, other sweetened beverages, and fruit juice, may be major contributors to childhood obesity. One study reported that drinking soda regularly increases a child’s risk for obesity by 60%. The average American adolescent consumes 15 to 20 extra teaspoons a day just from soda and sugary drinks. (Juice, while better than soda, is still filled with sugar.)
• Less physical exercise and greater sedentary activities play another significant role in obesity in children. A high level of physical activity--not just using up energy--is important for weight control in young people. Unfortunately, according to one study, the annual distance walked by children has fallen by nearly 30% since 1972, partially because more parents are driving their children to school out of fear of abduction, molestation, and traffic accidents. Schools are also offering fewer opportunities for daily physical activities than in the past.

Neither the media nor the educational system has strong well-financed programs that encourage healthy alternatives, including exercise and healthy foods.

Family History. Parental obesity more than doubles the risk that a young child, whether thin or overweight, will become obese as an adult. In older children and teenagers, obesity in parents starts to count less as a predictor for body weight than their own weight. The risk for may be due to environmental or genetic factors, or both.

Ethnic and Socioeconomic Factors. As in adult populations, children from lower socioeconomic groups and minority populations are at higher risk for obesity. For example, among young Mexican Americans and African Americans, there has been an increase in overweight prevalence of about 13% to over 23%.

Factors Surrounding Birth. The following factors surrounding birth are associated with a child's weight:

• Low birth weight is a risk factor for later obesity and diabetes. One theory is that humans have a "thrifty gene" that produces metabolic changes in infants with low birth weight. Such changes affect insulin and fat accumulation in order to produce a "catch-up" weight in these young children as quickly as possible. This rapid weight gain in infancy increases the gain risk for obesity in children and also in young adulthood.
• In a study of African American children, having an overweight pregnant mother increased the risk for later weight gain, but low birth weight did not.

Although some small studies have reported protection against obesity from breastfeeding, evidence is weak. In a 2003 study, for example, children who were breast fed for three to five months had a lower risk for obesity, but prolonged breastfeeding had no effect. Nevertheless, given the healthful effects of breast feeding and the possibility that it may have even a slight impact on childhood obesity, it is highly recommended.

Biologic Effect of Childhood Obesity on Adult Weight

Achieving a healthy weight becomes more difficult as children get older. The odds of obesity persisting into adulthood ranges from 20% in 4 year olds to 80% in teenagers. One reason for the persistence is biological. The fat cells change in number or mass depending on a person's age:

• Fat cells themselves multiply during two growth periods: early childhood and adolescence. Overeating during those times increases the number of fat cells. Some people are also just born with more fat cells.
• After adolescence, fat cells tend to increase in mass rather than quantity, so that adults who overeat and gain weight tend to have larger fat cells, not more of them. This growth in mass may be responsible for the greater risk for persistent obesity among teenagers than in small children who are overweight. Losing weight in after adolescence reduces the size of the fat cells but not their number, so weight loss becomes much more difficult.

Health Consequences of Childhood Obesity

Children and adolescents who are obese have poorer health than other children. Studies are reporting unhealthy cholesterol levels and high blood pressure in obese children and adolescents. Of great concern is the dramatic increase in type 2 diabetes in young people, which is most certainly largely due to the increase in obesity. Obesity in children is also linked to asthma, gallbladder problems, sleep apnea, and liver abnormalities. Childhood obesity may be partly responsible for the declining age for onset of puberty in girls, with subsequent risks for breast cancer.

It is not clear yet how many of these childhood problems persist in people who achieve normal weight as adults. Staying overweight into adulthood certainly confers health risks.

Managing Overweight and Obese Children

Childhood obesity is best treated by a non-drug, multidisciplinary approach including diet, behavior modification, and exercise. Some evidence suggests that reducing calories by only 200 to 260 per day would prevent weight gain in most overweight children. Here some tips for children who are overweight:

• Limit or avoid if possible take out, fast foods, high-sugar snacks, commercial packaged snacks, soda and sugar sweetened beverages (including too much juice).
• Let children snack but make sure the snacks are healthy. Eating small frequent healthy meals (instead of two or three large ones) has been associated with being thinner and having a better cholesterol profile.
• Let children choose their own food portions. One study indicated that children naturally ate 25% less then they chose their own portion size. When they were given larger portions their bite sizes were larger and they ate more.
• Don't criticize a child for being overweight. It does not help and such attitudes could put children at risk for eating disorders, which are equal or even greater dangers to health.
• Limit television, video games, and computer use to a few hours a week. This can contribute significantly to weight control, regardless of diet and physical activity.
• For young children, try the traffic-light diet. Food is designated with stoplight colors depending on their high caloric content: Green for go (low calories); yellow for "eat with caution" (medium calories); red for "stop" (high calories).
• Try a low-glycemic index diet. This may be as beneficial and possibly more than a standard reduced-fat diet in obese children. Such a diet focuses on carbohydrates, such as dried beans and soy, that raise blood sugar more slowly than others. This diet is sometimes used in diabetes and as a dietary approach in overweight adults. [See In-Depth Report #42, Diabetes diet.]