Childhood Obesity: Is a U.S. Epidemic Improving?

Overweight or obese children in America

According to the Centers for Disease Control and Prevention (CDC), obesity affects 17 percent of all children and adolescents in the United States, which equates to 12.5 million children – triple the rate from 1980. Hispanic boys and African-American girls are significantly more like to be obese than their non-Hispanic, white counterparts. In the United States, rates of being overweight or obese among children aged 2 to 19 are: Mexican-Americans, 38 percent; blacks, 34.9 percent; and whites, 30.7 percent. Additionally, one of seven low-income, preschool-aged children is obese.

Childhood obesity is a national public health concern for the United States.

However, a recent report from federal health authorities in February 2014 provides some encouraging news. Childhood obesity rates have dropped close to 43 percent among the 2- to 5-year-old age group over the last 10 years. This drop is the first decline seen for childhood obesity, which recent research suggests can lead to further weight gain and increased risks for cancer, heart disease and strokes as an adult. There are concerns that the number of children in the sample between 2 to 5 years of age was small, which may have skewed results, and that obesity rates (18 to 20 percent) remained high in older children and adolescents.

Overweight or obese children run the risk of having serious health-related risks at an early age1:

  • High blood pressure and high cholesterol can lead to heart disease
  • Impaired glucose control and insulin resistance can lead to type 2 diabetes
  • Excess weight can lead to joint problems
  • Fatty liver disease, gallstones and reflux disease
  • Psycho-social issues due to body image which may continue into adulthood

What Causes Childhood Obesity?
Being overweight or obese usually stems from one problem: eating too many calories and not getting adequate exercise to burn off excess consumed calories. Many factors can play into the

excess consumption of calories and weight gain in children2:

  • Selection and provision of unhealthy and calorie-laden food and beverages at home, school, and daycare
  • Sugary drinks, vending machine and fast-food access are associated with excess calorie consumption
  • Lack of daily exercise at home and at school prevents calorie burning, and lack of open-space in neighborhoods hinders access to play areas. It is recommended that children get at least one hour of aerobic, physical activity each day.
  • Inadequate portion control leads to excess calories at mealtime
  • Lack of education and support for breastfeeding, which is associated with a reduced risk for childhood obesity
  • Use of electronics, such as computers, video game consoles, and television viewing can interfere with time for exercise

How is Body Mass Index (BMI) calculated for children and adolescents?
Body Mass Index (BMI) is a screening tool used to access weight issues in children. The CDC and the American Academy of Pediatrics suggest using the BMI tool at age two years and older. For children, BMI is used to screen for obesity, overweight, healthy weight, or underweight. However, BMI is not a diagnostic tool. For example, a child may have a high BMI for age and sex, but to determine if excess fat is a problem, a health care provider would need to perform further assessments. These assessments might include:

  • skinfold thickness measurements
  • evaluations of diet and physical activity
  • review of family history of weight-related health risks
  • other appropriate health screenings.

BMI is calculated in the same way for children over two years of age, adolescents, and teenagers as it is for adults. However, the chart used to interpret the results is different because certain factors, such as age and gender, affect the amount of body fat in a child. The Centers for Disease Control (CDC) growth charts incorporate these differences and allow translation of a BMI number into a percentile rank based on a child’s gender and age.3 For children and adolescents 2 to 19 years of age:

  • Underweight is defined as a BMI lower than the 5th percentile
  • Healthy weight is defined as a BMI at or above the 5th percentile to lower than the 85th percentile
  • Overweight is defined as a BMI at or above the 85th percentile and lower than the 95th percentile for children of the same age and gender.
  • Obesity is defined as a BMI at or above the 95th percentile for children of the same age and gender.

Although the BMI number is calculated the same way for children and adults, the criteria used to interpret the meaning of the BMI number for children and teens are different from those used for adults.4 For children and teens, BMI age- and sex-specific percentiles are used for two reasons:

  • The amount of body fat changes with age.
  • The amount of body fat differs between girls and boys.

Because of these factors, the interpretation of BMI is both age- and sex-specific for children and teens. The CDC BMI-for-age growth charts take into account these differences and allows translation of a BMI number into a percentile for a child’s sex and age. A pediatrician will determine the pediatric BMI at each yearly well visit.