Dr. Alan Greene on Childhood Obesity

I've learned that my 4-year-old daughter is considered obese at 43 inches tall and 72 pounds. What causes obesity and how is it treated?

Obesity, or overnutrition, is the generalized accumulation of fat both beneath the skin and throughout the body. Some children are big, or stocky, because they have large skeletal frames. They are not obese. There are general guidelines for appropriate weight for a given height, but these are only general guidelines.

For a girl who is 43 inches tall, the average weight is 40 pounds. Anywhere between 33 and 46 pounds would be considered healthy. Your daughter, at 72 pounds, is significantly outside this range.

Obesity is usually caused by an individual's eating more food than is necessary for him or her. Participating in less physical activity than the individual needs can also cause obesity, but this is less common in children. Certain children may also inherit a genetic predisposition to obesity. They may eat the same diets as thinner children, but store more of the calories as fat.

The body stores new fat either by increasing the number of fat cells or by increasing the size of existing cells. It is particularly important to control childhood obesity since new fat cells are primarily formed during childhood. Each year of adding these extra fat cells makes adult obesity more difficult to fight.

Overweight children are not gluttonous or lazy. In fact, many studies have shown that obese children do not eat more calories than their peers. And by actually measuring caloric expenditure, investigators have shown that obese children actually expend more energy than their nonobese counterparts. Obese children need less food and more activity than their peers.

A variety of hormonal disorders, including problems with insulin, hypothalamic hormones, and pituitary hormones, can cause severe obesity. There are also a number of rare inherited syndromes (such as Laurence-Moon-Biedl, Prader-Willi, and Cushing) that create obesity. If a child's height is appropriate or advanced for her age, one of these underlying medical conditions is extremely unlikely. On the other hand, an obese child with slow height growth should certainly be evaluated.

Obesity is very difficult to treat, since it involves permanently changing basic eating and exercise habits. Successes almost always involve changing the whole family's habits to ones appropriate for the obese child. Cutting excess intake is best achieved by first keeping a careful record of food consumed, to identify particularly high-fat or high-calorie problem areas in the diet. The entire family must learn what fat is and which foods are high in fat (such as cheese, butter, margarine, nuts and nut butters, oil, red meat, fried foods, most processed fast foods or snack foods, etc.). Instead, whole fruit, whole vegetables, and whole grains should make up the bulk of the diet. Whatever the daily activity level of the family, it should be modestly increased.

Most families are not able to make these lasting changes on their own, and will benefit from meeting with an independent party at least once a week for 12 weeks. Ideally this outside individual would be a nutritionist or an expert in weight management, but even a committed friend would do. In many cities pediatric weight management programs such as Shapedown are available and are very effective. Whatever the source, monitoring should continue at least monthly for the remainder of the first year, and then every three to four months until the new habits have become very deeply ingrained.

(Shapedown is a program that was started at the University of California at San Francisco. You can obtain information about that program or similar programs in other areas by calling 415-453-8886 or by visiting www.shapedown.com.)

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.