Children who regularly consume more calories than they use will gain weight. If this is not reversed, the child will become obese over time. Many different factors contribute to this imbalance between calorie intake and consumption.

Genetic factors

• Obesity tends to run in families.

• A child with an obese parent, brother, or sister is more likely to become obese.

• Genetics alone does not cause obesity. Obesity occurs only when a child eats more calories than he or she uses.

Dietary habits

• Children's dietary habits have shifted away from healthy foods such as fruits, vegetables, and whole grains to a much greater reliance on fast food, processed snack foods, and sugary drinks.

• These foods tend to be high in fat and/or calories and low in many other nutrients.

• Some eating patterns that have been associated with this behavior are eating when not hungry and eating while watching TV or doing homework.

Socioeconomic status

• Low family incomes and having nonworking parents are associated with greater calorie intake for activity level.

Physical inactivity

• The popularity of television, computers, and video games translates into an increasingly sedentary (inactive) lifestyle for many children in the United States.

• Children in the United States spend an average of over 3 hours per day watching television. Not only does this use little energy (calories), it also encourages snacking.

• Fewer than half of children in the United States have a parent who engages in regular physical exercise.

• Only one third of children in the United States have daily physical education at school.

• Parent's busy schedules and fears about safety prevent many children from taking part in after-school sports programs.

Certain medical conditions can cause obesity, but these are very rare. They include hormone or other chemical imbalances and inherited disorders of metabolism.

Certain medications can cause weight gain by altering how the body processes food or stores fat.

When to Seek Medical Care

• If you think your child is overweight

• If your child has expressed concerns about his or her weight.

• If your child has problems keeping up with peers in physical fitness or sports.

Exams and Tests

Weight-to-height tables.

These tables give general ranges of healthy weights and overweight for a child’s height. Many health care providers define obesity in a child as weighing 20% or more over the healthy range. The tables, however, do not take into account the individual characteristics of each child. The health care provider must consider the child’s age and growth pattern when interpreting the chart. For example, some children gain weight before a growth spurt. This doesn’t mean they are becomingobese

Body fat percentage

The percentage of body weight that is fat is a good marker of obesity. Boys with more than 25% fat and girls with more than 32% fat are considered obese. Body fat percentage is difficult to measure accurately, however. The most accurate methods use special equipment that is not found at most medical offices. A method that measures skin fold thickness is not reliable unless it is done correctly by a trained and experienced technician.

Body mass index (BMI)

This measure is used to assess weight relative to height. It is the same as the body mass index used to identify adult obesity. It is defined as weight in kilograms divided by height in meters squared (kg/m 2). It also can be calculated in pound and inches. BMI is closely related to body fat percentage but is much easier to measure.

BMI is the standard for defining obesity in adults, but its use in children is not accepted universally. The Centers for Disease Control and Prevention (CDC) suggests two levels of concern for children based on the BMI-for-age charts. At the 85th percentile and above, children are "at risk for overweight" and at the 95th percentile or above, they are "overweight. " The American Obesity Association defines those children above the 95th percentile as "obese," which corresponds to a BMI of 30 (considered obese in adults).

To calculate a child’s body mass index, follow these steps

• Multiply the child’s weight in pounds by 705

• Then divide by the child’s height in inches.

• Divide this by the height in inches again.