Obesity may be defined as having a body weight that places one at significant risk for adverse health outcomes. Both obese and overweight children experience a lower quality of life man normal- weight children1, and, with severe obesity, the impairment is comparable to other serious chronic diseases.2 A majority of overweight children will become overweight adults3 and experience a shortened life expectancy4 with higher rates of disease and higher health care costs.
Guidelines are available to identify and evaluate overweight and obese children and adolescents to determine the need for treatment.5,6 Three categories of children are targeted for weight loss: children ages 2 to 7 with a body mass index (BMI) greater than the 95th percentile and an overweight-related comorbid disease; children older than age 7 who are overweight or at risk for overweight and have an overweight-related comorbid disease; and all children older than age 7 who are overweight.5 Both shortand long-term efficacy have been shown in the treatment of overweight children. The approach to weight loss in overweight school-aged children and adolescents is the focus of this article (Sidebar 1, see page 41).
A strategy of early intervention allows targeting of children at increased long-term risk for obesity and overweight-related disease when treatment is most likely to be successful. Primary care physicians are ideally positioned to carry out this strategy by calculating and plotting BMI on a yearly basis throughout childhood.7 If a diagnosis of overweight or obesity is established, the next steps are to consider the possibility of definable causes and to determine the presence of comorbid disease.
The major genetic or endocrine causes of early overweight or obesity include findings of mental retardation, deafness, or short stature. The most commonly used medications associated with pathological weight gain are corticosteroids, anti-convulsants, and antipsychotics. In particular, the atypical antipsychotics such as olanzapine, clozapine, and risperidone may lead to tremendous weight gain and the development of diabetes.
It is critical from the onset that physicians, parents, and children have mutually agreeable goals. This allows for open dialogue and assures that everyone is working toward the same end. Goals should be realistic, of concrete duration, and revised over time. The appropriate end-point will vary greatly by age, severity of obesity, and associated comorbid disease.
For adults, the Institute of Medicine has defined successful weight loss as 5% or more of initial body weight and the maintenance of this loss for at least 1 year.8 This degree of weight loss can improve serum cholesterol, glucose, and insulin levels, as well as blood pressure. Sleep apnea and nonalcoholic fatty liver commonly require a 10% reduction in body weight for improvement.
Optimal amounts of weight loss for achieving health goals have not been established for children or adolescents.
However, a 5% to 10% reduction in body weight can be expected to provide substantial health benefits. If rapid weight loss is required, then referral to an obesity center should be made.5
For those children without serious comorbidities, a good initial goal is no weight gain. For the child who has been gaining steadily, this is an important accomplishment. When a child has demonstrated a stable weight for 3 months, the goal can then shift to weight loss, with an initial goal of a 5% reduction in body weight. When this is achieved, the goal should then shift to weight maintenance. After 3 months of weight maintenance, the focus may be shifted back to weight loss if a patient remains obese and continues to have comorbidities. This step- wise approach allows for gradual, achievable progress. The concept also demonstrates to a parent and child that treatment is a longterm process.
The major problem in the diet of overweight and obese children is excessive calorie intake. Depending on the severity of overweight, dietary intervention may range from a minor modification to profound changes (Table 1). The best available data from studies of weight loss in adults suggest total calorie intake, not diet composition, determines weight loss over a short time period.9 There is insufficient evidence regarding long-term weight loss and or maintenance. Whether diet composition in ad libitum conditions leads to differences in long-term energy intake remains an open question.10
Fat has been the major target of dietary change because it has the greatest caloric density. Rather than simply reducing fat intake in isolation, a moderately low-fat, reduced-calorie diet is the cornerstone of weight-loss therapy for all age groups. On such a diet, a child can be expected to lose weight. The principle is to increase intake of complex carbohydrates and dietary fiber through fruit, vegetables, and whole grains while decreasing the consumption of energy-dense foods with a highfat content. Common examples include the traffic light diet" and the National Cholesterol Education Program (NCEP) Steps I and II diets.12
Potential Dietary Strategies for Weight Management
The traffic light diet separates foods into red, yellow, and green categories to simplify the understanding of what foods to eat and not eat. In doing so, the amount of foods that are calorically dense and have low nutritional values are reduced.
The NCEP diets are designed to reduce cholesterol. The Step I Diet calls for an intake of total fat less than 30% of calories, saturated fatty acids less than 10% of calories, and cholesterol less than 300 mg per day. The Step ? Diet requires a reduction in saturated fatty acids to less than 7% of calories and cholesterol to less than 200 mg per day. When combined with high-fiber intake and reduced calories, the NCFJP diets provide balanced nutrition and promote weight loss. The challenge is successfully following a diet in the short-term and long-term.
As carbohydrates have received more attention recently, the appropriateness of a low-fat diet has been widely called in to question. Simple sugars, particularly in the form of sweetened beverages, are an important source of calories.13 Small initial studies suggest some promise for strategies focused on carbohydrate amount or type (see Table 1, see page 4 1).14 There is insufficient evidence to recommend for or against the use of such diets.15 There are some data regarding the use of a low-carbohydrate strategy in the context of a protein-sparing modified fast.16
Behavioral Therapy Tools for Weight Management
In severely obese children and adolescents, medically supervised verylow-calorie diets may achieve rapid weight loss.17 These diets carry increased risk for complications such as arhythmias, gallstones, and possibly worsening fibrosis in the context of nonalcoholic steatohepatitis and still require long-term lifestyle modifications to avoid weight regain.
One or more meals per day may be replaced with a commercially available, portion-controlled beverage or meal that is vitamin and mineral fortified. The strength of this strategy is that the decision-making aspect of food selection and preparation is simplified. Also, typical meal replacement options are designed to provide adequate nutrition in a lower number of calories. There are no published studies of meal replacement in children or adolescents; however, practical experiences, published trials in adults, and ease of use make this strategy a reasonable dietary option.18
Physical activity is an important means of preventing disease but usually is not a sufficient tool to promote weight loss by itself.11 This is because it is much harder to burn as many calories through exercise as can be eliminated by dietary change. For example, 30 to 45 minutes of moderate activity will burn approximately 150 calories, compared with the reduction of 500 calories per day recommended by dietary change. However, physical activity is additive, has health benefits beyond weight loss, and is essential for preventing weight regain. Additionally, decreasing sedentary activities such as television or Internet usage may be effective in increasing total energy expenditure.'9·20
Behavioral modification provides tools to overcome barriers in making lasting dietary and activity changes.
Although not effective in isolation, behavioral therapy has been shown to be an important component of successful weight management. Examples of behavioral techniques are outlined in Table 2, and detailed reviews are available.21
Criteria for referral of overweight children are shown in Table 3 (see page 43). Potential needs may include endocrinology, gastroenterology, genetics, nutrition, pulmonology, orthopedics, otolaryngology, and psychology. Furthermore, clinicians should establish a relationship with a comprehensive obesity management program, often located at a university or children's hospital. A copy of the program's criteria for referral should be obtained, as well as a list of measurements than can be performed through the clinician's office before and after participation. Waiting lists can be long, and streamlining the referral process and facilitating insurance authorization can be helpful for patients.
Limited published data exist regarding the use of medications or surgery in people younger than 18 years of age. These options are discussed to provide a more complete review, but without better data on safety and efficacy, their use should be restricted to consultations with experts in the treatment of pediatric overweight and obesity.22
Medication should be part of a comprehensive strategy when used. Two medications are labeled for long-term use. An appetite suppressant, sibutramine, is labeled for those as young as 16 and was reported in a controlled pediatric trial.23 Sibutramine inhibits the reuptake of norepinephrine and serotonin. In a group of severely obese adolescents, 63% of subjects achieved a reduction in BMI greater than or equal to 5% from baseline after 6 months of treatment with sibutramine in conjunction with behavioral therapy, compared with 36% with behavioral therapy alone. Because of the effects on heart rate and blood pressure, approximately one-half of the subjects required a dosage adjustment, and some were unable to tolerate the medication.
The second medication, orlistat, is an inhibitor of fat absorption and is not currently labeled for use by patients younger than 18. An open-label pilot trial was conducted with orlistat in early adolescents with morbid obesity and overweight-related co-morbidities.24 A mean weight loss of 4% of body weight was achieved in 3 months in this difficult-to-treat population. No controlled or long-term pediatric data are yet available.
Several other medications, although labeled for others, may have a role in the treatment of overweight and obesity but have not been proven and have potential side effects. These include strategies to improve insulin sensitivity (eg, metformin) or to decrease appetite (eg, topiramate, fluoxetine, buproprion).25"27
An additional note of caution is warranted regarding thyroid hormone supplementation. In a euthyroid individual, the addition of thyroid hormone not only is ineffective in reducing adipose tissue but is likely to promote loss of lean body mass and cause negative nitrogen balance.28 Thus, in the absence of hypothyroidism, thyroid supplementation has no role in the treatment of overweight and obesity.
Surgery has a role for a small subset of morbidly obese adolescents. However, there is a paucity of existing data due to limited reporting, short-term follow up, and high rates of patients lost to follow up. Many bariatric surgery centers operate on adolescents, and several children's hospitals have initiated programs.29·30 Guidelines for candidate selection can be expected soon. Multicenter data will be required to understand the rates of long-term success in weight loss and improvement in health status, as well as the resultant morbidity and mortality.
Criteria for Referral of Overweight Patients
Fundamental questions regarding treatments and outcomes remain and should be a research priority. A majority of interventions have been conducted in obese préadolescent children with mild to moderate obesity and without significant comorbidities. To determine who to treat, we need to include more adolescents, subjects with morbid obesity, and subjects of Asian/Pacific Islander race or of Hispanic ethnicity. These studies will need to address the effects of culture and genetics on treatment efficacy.
One of the most fundamental questions is what diet to recommend. The optimal diet for successful long-term weight loss is controversial and requires controlled clinical trials. As for when to intervene with medication, the goal of treatment is to reduce the development and progression of overweight-associated comorbidity. Thus, future studies will need to address the effect of pharmacotherapy on clinically relevant endpoints. We also must determine how to deliver the appropriate care practically. A major barrier to the identification and treatment of overweight and obese children is the lack of insurance reimbursement for prevention or treatment. Future research will need to document the real cost of childhood overweight and demonstrate the effects of intervention on multiple outcomes, including disease, quality of life, and healthcare costs.
Because overweight and obesity are chronic health conditions, long-term management is necessary, with particular attention to comorbidities. Lifestyle modification including changes in diet and activity can be accomplished in the primary care setting. Many overweight and obese children and adolescents can achieve weight loss of 0.5 kg per week even over long periods. For some severely obese children, pharmacotherapy or surgery may be necessary.
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Effects of decreasing sedentary behavior and increasing activity on weight change in obese children. Health Psychol. 1995;14(2):109115.
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Potential Dietary Strategies for Weight Management
Behavioral Therapy Tools for Weight Management
Criteria for Referral of Overweight Patients