Overweight Children and Adolescents
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《新英格兰医药杂志》
This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the authors' clinical recommendations.
A seven-year-old girl is 130 cm tall (51 in., the 90th percentile for girls of the same age) and weighs 34.6 kg (76 lb, above the 95th percentile), with a body-mass index (defined as the weight in kilograms divided by the square of the height in meters) of 20.5 (above the 95th percentile). Physical examination reveals no abnormalities aside from her excess weight. Her family eats at a quick-service restaurant once a week, and she drinks approximately 16 oz (450 ml) of soft drinks and 8 oz (225 ml) of whole milk per day. Her physical activity is limited to 30 minutes of physical education twice per week and 20-minute recesses three days per week in school. She has approximately 4.5 hours of screen time per day, which is divided among the television sets in her bedroom and in the family room and the family computer. What should you advise?
The Clinical Problem
Childhood overweight, defined as a body-mass index at or above the 95th percentile for children of the same age and sex, affected approximately 15 percent of children and adolescents in the United States in the period from 1999 through 2002. According to the National Health and Nutrition Examination Surveys, the prevalence of overweight children doubled between 1976–1980 and 1999–2002.1 Although the prevalence of overweight among blacks, Mexican Americans, and Native Americans exceeds that of other ethnic groups, overweight has increased among both sexes and among all racial, ethnic, and socioeconomic groups. The risk for overweight is increased among persons with high birth weight (4000 g or more)2 and parental obesity.3
Childhood overweight is associated with a variety of adverse consequences. For example, more than 60 percent of overweight children 5 to 10 years of age in Bogalusa, Louisiana, had at least one risk factor for cardiovascular disease, such as elevated blood pressure or serum insulin levels or dyslipidemia, and 25 percent had two or more risk factors.4 Type 2 diabetes now accounts for up to 45 percent of all newly diagnosed diabetes in pediatric patients5 and is more common in ethnic and racial groups with higher rates of obesity, such as Native Americans, blacks, and Mexican Americans. Conditions associated with overweight, such as sleep apnea and gallbladder disease, tripled in children and adolescents between 1979–1981 and 1997–1999.6 Although childhood-onset overweight accounts for only 25 percent of adult obesity, overweight that begins before age eight and persists into adulthood is associated with a mean body-mass index of 41 in adulthood, as compared with a body-mass index of 35 for adult-onset obesity.7
Strategies and Evidence
Assessment
Measurement of the body-mass index represents the first step in assessment and treatment. The term "overweight" is applied when the body-mass index of a child exceeds the 95th percentile for children of the same age and sex, and the term "at risk for overweight" is applied to children or adolescents whose body-mass index is between the 85th and 95th percentiles (Figure 1). 8,9 A body-mass index at or above the 95th percentile is highly specific for increased body fat.10 The crossing of major growth percentile lines upward is an early indication of risk. However, body-mass index must also be considered in the context of the age of the child and the growth patterns of the family. In children who are born small but are genetically programmed to be larger, these adjustments appear to occur in the first five years of life. Less than 5 percent of children cross two major percentile lines upward on the growth charts of the Centers for Disease Control and Prevention after four years of age.11 Thereafter, children who cross major percentile lines upward may be at increased risk for overweight. Although visceral fat increases the likelihood of morbidity in adults and youth, no widely accepted clinical measure of central adiposity yet exists for youth.
Figure 1. Body-Mass Index and Percentiles.
The charts were compiled by the Centers for Disease Control and Prevention on the basis of combined data from several nationally representative surveys of the U.S. population that were collected between 1963 and 1980. Overweight is defined as a body-mass index (the weight in kilograms divided by the square of the height in meters) at or above the 95th percentile on these growth charts. Because the data on which these charts are based were collected before 1980, more than 5 percent of the current population may be classified as overweight.
The family history of obesity and obesity-related diseases and the dietary and activity patterns should routinely be assessed (Table 1). The signs and symptoms that are most frequently associated with a congenital or endocrine abnormality underlying overweight are hypogonadism, short stature, dysmorphic features, a somatic abnormality, and mental retardation (Table 2). Clinical experience in tertiary care centers suggests that identifiable endocrine abnormalities or syndromes account for less than 1 percent of cases of overweight. The history and physical examination should also address potential complications of overweight (Table 2).
Table 1. Assessment of Childhood Overweight.
Table 2. Symptoms and Signs of Syndromes Associated with or Complications of Overweight in Children and Adolescents.
Laboratory Testing
A fasting profile of lipoprotein, insulin, and glucose levels has been recommended by some experts for all overweight children.23,24 Elevated levels of liver enzymes, which usually indicate hepatic steatosis, occur in approximately 10 percent of overweight children and adolescents in the general population.25 As with all screening tests, clinicians should decide whether testing is likely to alter the course of treatment they prescribe. The American Diabetes Association recommends a fasting plasma glucose test for children 10 years of age or older who have a body-mass index at or above the 85th percentile and two of the following risk factors: a family history of type 2 diabetes in first-degree or second-degree relatives, nonwhite race, and conditions associated with insulin resistance (e.g., acanthosis nigricans, hypertension, dyslipidemias, or polycystic ovary syndrome).26 It is uncertain how many children and adolescents meet these criteria, and the cost-effectiveness of this approach is unknown.
Communication
Providers report that they are often reluctant to discuss overweight with families because of the associated stigma, the concern that parents will feel blamed, or fears that a discussion of weight will lead to an eating disorder. However, when providers address obesity in obese adults, those adults are more likely to initiate weight-control efforts than when weight is not discussed.27 In the absence of a complication that needs urgent attention, a neutral approach to weight control in a child may help to avoid a sense of blame or pressure and to assess the family's readiness to change. For example, the level of parental concern can be elicited by such questions as "Are you concerned about your child's weight?" and "Has your child's weight caused her any problems?" Because "obesity" is often a pejorative term and is popularly used to indicate a massive degree of overweight, the term "overweight" is preferable when discussing weight with parents.
Treatment
Treatment to achieve weight maintenance is recommended23 for children two to six years of age who have a body-mass index at or above the 95th percentile for their age and sex and who do not have weight-related complications. Weight loss is indicated for two-to-six-year-old children who have a weight-related complication and for older children whose body-mass index is at or above the 95th percentile whether or not they have a weight-related complication. Overweight-related conditions requiring more urgent weight loss include pseudotumor cerebri, sleep apnea, orthopedic abnormalities, type 2 diabetes, and hypertension. Additional factors that increase the need for treatment include major psychological or social complications and an increased risk of a future obesity-associated illness as suggested by a family history of obesity, type 2 diabetes, or cardiovascular disease in a first-degree or second-degree relative.23,24,26
Family engagement is critical to therapy. If the child, one or both parents, or the guardians are not motivated, any treatment is likely to fail and frustrate everyone involved. Under such circumstances, clinicians should share the basis for their concern about the child's weight and reinforce positive behaviors that are already in place. Motivation should not be viewed as an all-or-nothing phenomenon but, rather, as a dynamic process that providers can influence over time. Parental concerns other than the child's overweight also may help to address behaviors that contribute to it. For example, concern about schoolwork, family time, or exposure to televised sex and violence may be a more powerful motivator to control television time than is overweight.
Specific Interventions
A systematic review of randomized, controlled trials of lifestyle interventions for the treatment of pediatric overweight concluded that most studies were too small and that the number of studies was insufficient to compare the efficacies of various treatment approaches or components.28 In the absence of such data, studies of treatments in research settings29,30 and of adult obesity31,32 provide useful direction. In children, behavior modification has generally produced losses of 5 to 20 percent of excess weight, of 1 to 3 units of the body-mass index, or both, over 3 to 6 months; changes reported over 6 to 12 months range from a 25 percent loss to a 10 percent increase in excess weight, a loss of 0 to 4 units of the body-mass index, or both. Long-term follow-up, as reported by a single research group, has shown increases of about 3 percent to decreases of about 20 percent in excess weight after 2 to 10 years.30
Four main interrelated behavioral strategies are used to help families make changes: controlling the environment, monitoring behavior, setting goals, and rewarding successful changes in behavior. The targets for these strategies must be age-specific. For example, it is the parent's responsibility to monitor the behaviors of young children, whereas adolescents may monitor their own behaviors. Key principles and examples of these weight-control strategies29,33 are summarized in Table 3.
Table 3. Strategies for and Principles of Weight Control.
Diet and Activity
Short-term weight loss in pediatric patients has been achieved in randomized, controlled trials involving various strategies for the control of diet and activity level. These strategies include calorie and fat reduction,29 adherence to a low-carbohydrate diet,34 the integration of physical activity into daily routines,29 participation in structured, vigorous physical activity,35 and the reduction of sedentary behaviors.36 If changes in diet and activity level produce a net energy deficit, weight loss will result. A substantial slowing of weight gain may be achieved by relatively small but consistent changes in energy intake, expenditure, or both (200 to 500 kcal per day).37,38
Because consensus is lacking on the most effective ways to achieve long-term weight control, the clinician, child, and family should work together to choose goals that can be achieved in terms of diet and activity. The monitoring of increases or decreases in weight allows the clinician to assess whether the changes in diet and activity level are too limited, sufficient, or too aggressive and to adjust these changes accordingly. Other providers, such as dietitians or nurse practitioners, also can help assess, change, and monitor behaviors. Group treatment of parents and children may provide more cost-effective and efficient delivery of care.
Weight-control interventions in medical settings are unlikely to succeed over the long term without alterations in the environments in which children and adolescents live. For example, efforts to change food choices may not succeed without the availability of healthful choices in school lunches or vending machines or without access to supermarkets where fruits and vegetables can be purchased at reasonable prices. Efforts to increase physical activity may not succeed if neighborhoods are unsafe for outdoor play or if physical education is absent in schools.
Weight Goals
A challenge in the treatment of overweight children involves the maintenance of normal growth and development with concurrent reductions in weight and body fat. For most overweight children, the first goal of weight control is weight maintenance.23 If weight loss is desired, an appropriate starting goal is about 1 lb (450 g) of weight loss per month.23 The long-term weight goal should be a body-mass index that is below the 85th percentile for age and sex, because the severity of adult obesity appears to be related to the severity and persistence of childhood overweight. Satisfactory weight control can also be assessed according to improvements in coexisting illnesses such as hyperlipidemia, hyperinsulinemia, acanthosis nigricans, and hypertension.
Complications of Treatment
Systematic studies of the complications of various approaches to treatment are needed. In one 10-year follow-up of overweight children who were treated in behavioral modification programs to reduce calorie intake and increase physical activity, participants reported substantial rates of major psychiatric disorders, primarily depression, eating disorders, and substance abuse.29 These rates may reflect a high level of risk among patients seeking treatment rather than effects of the intervention. Population-based surveys of adolescents indicate that an elevated body-mass index is associated with a higher risk of disordered eating behaviors.39
Addressing eating and activity behaviors may also exacerbate existing family conflicts, which in turn may require psychological therapy to accompany or precede treatment for weight control. Excessive weight loss reflects extreme calorie restriction. Growth retardation and nutritional insufficiency have been reported in children on highly restrictive diets that provide less than two thirds of the estimated energy needs,40 but such adverse events are extremely unlikely with respect to the approaches outlined here. Gallstones occur in 10 to 25 percent of adults who lose weight rapidly,15 but the frequency of this complication in pediatric patients is uncertain.
Prevention
The approaches described above also apply to the prevention of overweight in children of normal weight or in children at risk for overweight. School-based randomized trials have demonstrated that a reduction in television or total screen time41,42 and an increase in the frequency and intensity of activity during physical education classes43,44 are effective preventive measures. In the two studies that reported changes in the body-mass index, in children in the treatment group, the body-mass index increased at an annualized rate of about 0.8 to 1.3 units less than in the children in the control group.41,43
Observational studies suggest that breast-feeding may be another preventive strategy.45 Both breast-feeding and later physical activity46 have been associated with reduced weight gain or the prevention of weight-related coexisting illnesses; both are generally safe and have other benefits that warrant their implementation. Other strategies that appear promising but have not been tested in randomized trials include the reduced consumption of sugar-sweetened beverages,47 reduced portion sizes at mealtimes,48 and increased consumption of fruits and vegetables.49
Areas of Uncertainty
Data from randomized trials to support any particular strategy over others to achieve weight control in children and adolescents28 or to prevent the development of overweight50 are currently lacking. The approaches outlined above apply to children and adolescents who are mildly to moderately overweight. Patients for whom treatment is the most challenging are those who are severely overweight (with a body-mass index of 40 or more); these patients may benefit from treatment by providers with experience in the management of such cases. Aggressive approaches to treatment for severely overweight patients include drug therapy, restrictive carbohydrate-free, hypocaloric diets, and bariatric surgery. Each of these should be considered only after more conservative approaches fail.
The two drugs currently approved for the management of obesity are sibutramine, an inhibitor of norepinephrine, serotonin, and dopamine reuptake, and orlistat, a lipase inhibitor that inhibits the absorption of dietary fats. The safety and efficacy of sibutramine have not been established for patients less than 16 years of age, and orlistat has not been evaluated in patients less than 12 years of age. A six-month clinical trial of sibutramine in adolescents demonstrated that patients who were treated with this agent lost 4.6 kg more weight than did patients who received placebo.51 A 54-week clinical trial of orlistat in adolescents, as described in the package insert, found a significantly greater reduction in body-mass index among patients treated with orlistat than among those who received placebo. As with other chronic diseases, weight maintenance is likely to require ongoing drug therapy. As the authors of the sibutramine trial concluded, "Until more extensive safety and efficacy data are available, medications for weight loss should be used only on an experimental basis in adolescents and children."51
Hypocaloric diets containing less than 20 g of carbohydrate result in rapid weight loss and appear to block hunger.52 Their use in pediatric patients has been described52 but requires physician oversight and monitoring. There have been limited published reports of experience with bariatric surgery in the pediatric age group. Available recommendations suggest the limitation of its use to adolescents with a body-mass index of 40 or more who also have obesity-associated coexisting illnesses; the recommendations also specify criteria for referral and treatment.53
Guidelines
An expert committee that included representatives from the American Academy of Pediatrics, the American Dietetic Association, and the National Association of Pediatric Nurse Practitioners has issued consensus recommendations for the assessment and treatment of childhood and adolescent overweight.23 Consensus recommendations for the use of bariatric surgery in adolescents have also been published53 and endorsed by the American Pediatric Surgical Association.54 The recommendations of these organizations agree with those outlined here.
Summary and Recommendations
Several strategies are useful in the management of overweight patients who are seen in primary care settings, such as the seven-year-old girl described in the vignette. The routine assessment of body-mass index will allow providers to identify modest excesses of weight when the behaviors that contribute to them are tractable. Communication strategies that avoid blame and encourage concern and an interest in change on the part of overweight patients and their families are critical to management. Most causes and complications of overweight can be identified by medical history and physical examination. A fasting lipid profile is a reasonable test for all overweight children. The medical history (with attention to risk factors for diabetes or other complications), the physical examination (to rule out such conditions as acanthosis nigricans), and the likelihood that test results will affect the management of the case should guide further testing. Treatment should focus on habits of diet or activity that contribute to weight gain or impair weight loss and that can be modified; recommendations should be based on a sensitivity to competing family priorities, particularly in the absence of apparent complications of overweight. Relevant behaviors should be quantified to facilitate monitoring and change, and positive changes should be reinforced. In the case vignette, immediate targets for change suggested by the history include a reduction in the intake of soft drinks and in screen time and an increase in active play. Our initial goal for this patient would be to maintain her current weight for one year and to achieve a body-mass index that is below the 85th percentile for her age, assuming that she undergoes continued linear growth at the 90th percentile. We would recommend weekly to monthly face-to-face or telephone monitoring of behavioral and weight goals by the primary care provider. In some settings, nurses, dietitians, or other health professionals may help accomplish frequent follow-up assessments.
We are indebted to Barbara Polhamus for her assistance.
Source Information
From the Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, Atlanta (W.H.D.); and the Division of General Pediatrics and Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, Calif. (T.N.R.).
Address reprint requests to Dr. Dietz at the Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, 4770 Buford Hwy. NE, MS K-24, Atlanta, GA 30341, or at wcd4@cdc.gov.
References
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Weisberg LA, Chutorian AM. Pseudotumor cerebri of childhood. Am J Dis Child 1977;131:1243-1248.
Mallory GB, Fiser D, Jackson R. Sleep-associated breathing disorders in morbidly obese children and adolescents. J Pediatr 1989;115:892-897.
Erler T, Paditz E. Obstructive sleep apnea syndrome in children: a state-of-the-art review. Treat Respir Med 2004;3:107-22.
Everhart JE. Contributions of obesity and weight loss to gallstone disease. Ann Intern Med 1993;119:1029-1035.
Lavine JE, Schwimmer JB. Nonalcoholic fatty liver disease in the pediatric population. Clin Liver Dis 2004;8:549-558.
Kelsey JL, Acheson RM, Keggi KJ. The body build of patients with slipped capital femoral epiphysis. Am J Dis Child 1972;124:276-281.
McKenna TJ. Pathogenesis and treatment of polycystic ovary syndrome. N Engl J Med 1988;318:558-562.
Franks S. Polycystic ovary syndrome. N Engl J Med 1995;333:853-861.
Holm VA, Sulzbacher SJ, Pipes PL, eds. The Prader–Willi syndrome. Baltimore: University Park Press, 1981.
Green JS, Parfrey PS, Harnett JD, et al. The cardinal manifestations of Bardet-Biedl syndrome, a form of Laurence-Moon-Biedl syndrome. N Engl J Med 1989;321:1002-1009.
Dietz WH Jr, Gross WL, Kirkpatrick JA Jr. Blount disease (tibia vara): another skeletal disorder associated with childhood obesity. J Pediatr 1982;101:735-737.
Barlow SE, Dietz WH. Obesity evaluation and treatment: expert committee recommendations. Pediatrics 1998;102:e29-e29.
Williams CL, Hayman LL, Daniels SR, et al. Cardiovascular health in childhood: a statement for health professionals from the Committee on Atherosclerosis, Hypertension, and Obesity in the Young (AHOY) of the Council on Cardiovascular Disease in the Young, American Heart Association. Circulation 2002;106:143-160.
Strauss RS, Barlow SE, Dietz WH. Prevalence of abnormal serum aminotransferase values in overweight and obese adolescents. J Pediatr 2000;136:727-733.
American Diabetes Association. Type 2 diabetes in children and adolescents. Diabetes Care 2000;23:381-389.
Galuska DA, Will JC, Serdula MK, Ford ES. Are health care professionals advising obese patients to lose weight? JAMA 1999;282:1576-1578.
Summerbell CD, Ashton V, Campbell KJ, Edmunds L, Kelly S, Waters E. Interventions for treating obesity in children. Cochrane Database Syst Rev 2003;3:CD001872-CD001872.
Epstein LH, Valoski A, Wing RR, McCurley J. Ten-year outcomes of behavioral family-based treatment for childhood obesity. Health Psychol 1994;13:373-383.
Epstein LH, Myers MD, Raynor HA, Saelens BE. Treatment of pediatric obesity. Pediatrics 1998;101:554-570.
Wadden TA, Sarwer DB. Behavioral treatment of obesity: new approaches to an old disorder. In: Goldstein D, ed. The management of eating disorders and obesity. Totowa, N.J.: Humana Press, 1999:173-99.
Wing RR. Behavioral weight control. In: Wadden TA, Stunkard AJ, eds. Handbook of obesity treatment. New York: Guilford Press, 2002:301-16.
Robinson TN. Behavioural treatment of childhood and adolescent obesity. Int J Obes Relat Metab Disord 1999;23:Suppl 2:S52-S57.
Sondike SB, Copperman N, Jacobson MS. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factors in overweight adolescents. J Pediatr 2003;142:253-258.
Gutin B, Barbeau P, Owens S, et al. Effects of exercise intensity on cardiovascular fitness, total body composition, and visceral adiposity of obese adolescents. Am J Clin Nutr 2002;75:818-826.
Epstein LH, Paluch RA, Gordy CC, Dorn J. Decreasing sedentary behaviors in treating pediatric obesity. Arch Pediatr Adolesc Med 2000;154:220-226.
Hill JO, Wyatt HR, Reed GW, Peters JC. Obesity and the environment: where do we go from here? Science 2003;299:853-855.
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Killen JD, Taylor CB, Hayward C, et al. Pursuit of thinness and onset of eating disorder symptoms in a community sample of adolescent girls: a three-year prospective analysis. Int J Eat Disord 1994;16:227-238.
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Robinson TN. Reducing children's television viewing to prevent obesity: a randomized controlled trial. JAMA 1999;282:1561-1567.
Gortmaker SL, Peterson K, Wiecha J, et al. Reducing obesity via a school-based interdisciplinary intervention among youth: Planet Health. Arch Pediatr Adolesc Med 1999;153:409-418.
Flores R. Dance for health: improving fitness in African American and Hispanic adolescents. Public Health Rep 1995;110:189-193.
Dwyer T, Coonan WE, Leitch DR, Hetzel BS, Baghurst RA. An investigation of the effects of daily physical activity on the health of primary school students in South Australia. Int J Epidemiol 1983;12:308-313.
Dewey KG. Is breastfeeding protective against child obesity? J Hum Lact 2003;19:9-18.
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Ludwig DS, Peterson KE, Gortmaker SL. Relation between consumption of sugar-sweetened drinks and childhood obesity: a prospective, observational analysis. Lancet 2001;357:505-508.
Birch LL, Fisher JO. Development of eating behaviors among children and adolescents. Pediatrics 1998;101:539-549.
Epstein LH, Gordy CC, Raynor HA, Beddome M, Kilanowski CK, Paluch R. Increasing fruit and vegetable intake and decreasing fat and sugar intake in families at risk for childhood obesity. Obes Res 2001;9:171-178.
Campbell K, Waters E, O'Meara S, Kelly S, Summerbell C. Interventions for preventing obesity in children. Cochrane Database Syst Rev 2002;2:CD001871-CD001871.
Berkowitz RI, Wadden TA, Tershakovec AM, Cronquist JL. Behavior therapy and sibutramine for the treatment of adolescent obesity: a randomized controlled clinical trial. JAMA 2003;289:1805-1812.
Dietz WH Jr, Schoeller DA. Optimal dietary therapy for obese adolescents: comparison of protein plus glucose and protein plus fat. J Pediatr 1982;100:638-644.
Inge TH, Krebs NF, Garcia VF, et al. Bariatric surgery for severely overweight adolescents: concerns and recommendations. Pediatrics 2004;114:217-223.
Rodgers BM. Bariatric surgery for adolescents: a view from the American Pediatric Surgical Association. Pediatrics 2004;114:255-256.(William H. Dietz, M.D., P)
A seven-year-old girl is 130 cm tall (51 in., the 90th percentile for girls of the same age) and weighs 34.6 kg (76 lb, above the 95th percentile), with a body-mass index (defined as the weight in kilograms divided by the square of the height in meters) of 20.5 (above the 95th percentile). Physical examination reveals no abnormalities aside from her excess weight. Her family eats at a quick-service restaurant once a week, and she drinks approximately 16 oz (450 ml) of soft drinks and 8 oz (225 ml) of whole milk per day. Her physical activity is limited to 30 minutes of physical education twice per week and 20-minute recesses three days per week in school. She has approximately 4.5 hours of screen time per day, which is divided among the television sets in her bedroom and in the family room and the family computer. What should you advise?
The Clinical Problem
Childhood overweight, defined as a body-mass index at or above the 95th percentile for children of the same age and sex, affected approximately 15 percent of children and adolescents in the United States in the period from 1999 through 2002. According to the National Health and Nutrition Examination Surveys, the prevalence of overweight children doubled between 1976–1980 and 1999–2002.1 Although the prevalence of overweight among blacks, Mexican Americans, and Native Americans exceeds that of other ethnic groups, overweight has increased among both sexes and among all racial, ethnic, and socioeconomic groups. The risk for overweight is increased among persons with high birth weight (4000 g or more)2 and parental obesity.3
Childhood overweight is associated with a variety of adverse consequences. For example, more than 60 percent of overweight children 5 to 10 years of age in Bogalusa, Louisiana, had at least one risk factor for cardiovascular disease, such as elevated blood pressure or serum insulin levels or dyslipidemia, and 25 percent had two or more risk factors.4 Type 2 diabetes now accounts for up to 45 percent of all newly diagnosed diabetes in pediatric patients5 and is more common in ethnic and racial groups with higher rates of obesity, such as Native Americans, blacks, and Mexican Americans. Conditions associated with overweight, such as sleep apnea and gallbladder disease, tripled in children and adolescents between 1979–1981 and 1997–1999.6 Although childhood-onset overweight accounts for only 25 percent of adult obesity, overweight that begins before age eight and persists into adulthood is associated with a mean body-mass index of 41 in adulthood, as compared with a body-mass index of 35 for adult-onset obesity.7
Strategies and Evidence
Assessment
Measurement of the body-mass index represents the first step in assessment and treatment. The term "overweight" is applied when the body-mass index of a child exceeds the 95th percentile for children of the same age and sex, and the term "at risk for overweight" is applied to children or adolescents whose body-mass index is between the 85th and 95th percentiles (Figure 1). 8,9 A body-mass index at or above the 95th percentile is highly specific for increased body fat.10 The crossing of major growth percentile lines upward is an early indication of risk. However, body-mass index must also be considered in the context of the age of the child and the growth patterns of the family. In children who are born small but are genetically programmed to be larger, these adjustments appear to occur in the first five years of life. Less than 5 percent of children cross two major percentile lines upward on the growth charts of the Centers for Disease Control and Prevention after four years of age.11 Thereafter, children who cross major percentile lines upward may be at increased risk for overweight. Although visceral fat increases the likelihood of morbidity in adults and youth, no widely accepted clinical measure of central adiposity yet exists for youth.
Figure 1. Body-Mass Index and Percentiles.
The charts were compiled by the Centers for Disease Control and Prevention on the basis of combined data from several nationally representative surveys of the U.S. population that were collected between 1963 and 1980. Overweight is defined as a body-mass index (the weight in kilograms divided by the square of the height in meters) at or above the 95th percentile on these growth charts. Because the data on which these charts are based were collected before 1980, more than 5 percent of the current population may be classified as overweight.
The family history of obesity and obesity-related diseases and the dietary and activity patterns should routinely be assessed (Table 1). The signs and symptoms that are most frequently associated with a congenital or endocrine abnormality underlying overweight are hypogonadism, short stature, dysmorphic features, a somatic abnormality, and mental retardation (Table 2). Clinical experience in tertiary care centers suggests that identifiable endocrine abnormalities or syndromes account for less than 1 percent of cases of overweight. The history and physical examination should also address potential complications of overweight (Table 2).
Table 1. Assessment of Childhood Overweight.
Table 2. Symptoms and Signs of Syndromes Associated with or Complications of Overweight in Children and Adolescents.
Laboratory Testing
A fasting profile of lipoprotein, insulin, and glucose levels has been recommended by some experts for all overweight children.23,24 Elevated levels of liver enzymes, which usually indicate hepatic steatosis, occur in approximately 10 percent of overweight children and adolescents in the general population.25 As with all screening tests, clinicians should decide whether testing is likely to alter the course of treatment they prescribe. The American Diabetes Association recommends a fasting plasma glucose test for children 10 years of age or older who have a body-mass index at or above the 85th percentile and two of the following risk factors: a family history of type 2 diabetes in first-degree or second-degree relatives, nonwhite race, and conditions associated with insulin resistance (e.g., acanthosis nigricans, hypertension, dyslipidemias, or polycystic ovary syndrome).26 It is uncertain how many children and adolescents meet these criteria, and the cost-effectiveness of this approach is unknown.
Communication
Providers report that they are often reluctant to discuss overweight with families because of the associated stigma, the concern that parents will feel blamed, or fears that a discussion of weight will lead to an eating disorder. However, when providers address obesity in obese adults, those adults are more likely to initiate weight-control efforts than when weight is not discussed.27 In the absence of a complication that needs urgent attention, a neutral approach to weight control in a child may help to avoid a sense of blame or pressure and to assess the family's readiness to change. For example, the level of parental concern can be elicited by such questions as "Are you concerned about your child's weight?" and "Has your child's weight caused her any problems?" Because "obesity" is often a pejorative term and is popularly used to indicate a massive degree of overweight, the term "overweight" is preferable when discussing weight with parents.
Treatment
Treatment to achieve weight maintenance is recommended23 for children two to six years of age who have a body-mass index at or above the 95th percentile for their age and sex and who do not have weight-related complications. Weight loss is indicated for two-to-six-year-old children who have a weight-related complication and for older children whose body-mass index is at or above the 95th percentile whether or not they have a weight-related complication. Overweight-related conditions requiring more urgent weight loss include pseudotumor cerebri, sleep apnea, orthopedic abnormalities, type 2 diabetes, and hypertension. Additional factors that increase the need for treatment include major psychological or social complications and an increased risk of a future obesity-associated illness as suggested by a family history of obesity, type 2 diabetes, or cardiovascular disease in a first-degree or second-degree relative.23,24,26
Family engagement is critical to therapy. If the child, one or both parents, or the guardians are not motivated, any treatment is likely to fail and frustrate everyone involved. Under such circumstances, clinicians should share the basis for their concern about the child's weight and reinforce positive behaviors that are already in place. Motivation should not be viewed as an all-or-nothing phenomenon but, rather, as a dynamic process that providers can influence over time. Parental concerns other than the child's overweight also may help to address behaviors that contribute to it. For example, concern about schoolwork, family time, or exposure to televised sex and violence may be a more powerful motivator to control television time than is overweight.
Specific Interventions
A systematic review of randomized, controlled trials of lifestyle interventions for the treatment of pediatric overweight concluded that most studies were too small and that the number of studies was insufficient to compare the efficacies of various treatment approaches or components.28 In the absence of such data, studies of treatments in research settings29,30 and of adult obesity31,32 provide useful direction. In children, behavior modification has generally produced losses of 5 to 20 percent of excess weight, of 1 to 3 units of the body-mass index, or both, over 3 to 6 months; changes reported over 6 to 12 months range from a 25 percent loss to a 10 percent increase in excess weight, a loss of 0 to 4 units of the body-mass index, or both. Long-term follow-up, as reported by a single research group, has shown increases of about 3 percent to decreases of about 20 percent in excess weight after 2 to 10 years.30
Four main interrelated behavioral strategies are used to help families make changes: controlling the environment, monitoring behavior, setting goals, and rewarding successful changes in behavior. The targets for these strategies must be age-specific. For example, it is the parent's responsibility to monitor the behaviors of young children, whereas adolescents may monitor their own behaviors. Key principles and examples of these weight-control strategies29,33 are summarized in Table 3.
Table 3. Strategies for and Principles of Weight Control.
Diet and Activity
Short-term weight loss in pediatric patients has been achieved in randomized, controlled trials involving various strategies for the control of diet and activity level. These strategies include calorie and fat reduction,29 adherence to a low-carbohydrate diet,34 the integration of physical activity into daily routines,29 participation in structured, vigorous physical activity,35 and the reduction of sedentary behaviors.36 If changes in diet and activity level produce a net energy deficit, weight loss will result. A substantial slowing of weight gain may be achieved by relatively small but consistent changes in energy intake, expenditure, or both (200 to 500 kcal per day).37,38
Because consensus is lacking on the most effective ways to achieve long-term weight control, the clinician, child, and family should work together to choose goals that can be achieved in terms of diet and activity. The monitoring of increases or decreases in weight allows the clinician to assess whether the changes in diet and activity level are too limited, sufficient, or too aggressive and to adjust these changes accordingly. Other providers, such as dietitians or nurse practitioners, also can help assess, change, and monitor behaviors. Group treatment of parents and children may provide more cost-effective and efficient delivery of care.
Weight-control interventions in medical settings are unlikely to succeed over the long term without alterations in the environments in which children and adolescents live. For example, efforts to change food choices may not succeed without the availability of healthful choices in school lunches or vending machines or without access to supermarkets where fruits and vegetables can be purchased at reasonable prices. Efforts to increase physical activity may not succeed if neighborhoods are unsafe for outdoor play or if physical education is absent in schools.
Weight Goals
A challenge in the treatment of overweight children involves the maintenance of normal growth and development with concurrent reductions in weight and body fat. For most overweight children, the first goal of weight control is weight maintenance.23 If weight loss is desired, an appropriate starting goal is about 1 lb (450 g) of weight loss per month.23 The long-term weight goal should be a body-mass index that is below the 85th percentile for age and sex, because the severity of adult obesity appears to be related to the severity and persistence of childhood overweight. Satisfactory weight control can also be assessed according to improvements in coexisting illnesses such as hyperlipidemia, hyperinsulinemia, acanthosis nigricans, and hypertension.
Complications of Treatment
Systematic studies of the complications of various approaches to treatment are needed. In one 10-year follow-up of overweight children who were treated in behavioral modification programs to reduce calorie intake and increase physical activity, participants reported substantial rates of major psychiatric disorders, primarily depression, eating disorders, and substance abuse.29 These rates may reflect a high level of risk among patients seeking treatment rather than effects of the intervention. Population-based surveys of adolescents indicate that an elevated body-mass index is associated with a higher risk of disordered eating behaviors.39
Addressing eating and activity behaviors may also exacerbate existing family conflicts, which in turn may require psychological therapy to accompany or precede treatment for weight control. Excessive weight loss reflects extreme calorie restriction. Growth retardation and nutritional insufficiency have been reported in children on highly restrictive diets that provide less than two thirds of the estimated energy needs,40 but such adverse events are extremely unlikely with respect to the approaches outlined here. Gallstones occur in 10 to 25 percent of adults who lose weight rapidly,15 but the frequency of this complication in pediatric patients is uncertain.
Prevention
The approaches described above also apply to the prevention of overweight in children of normal weight or in children at risk for overweight. School-based randomized trials have demonstrated that a reduction in television or total screen time41,42 and an increase in the frequency and intensity of activity during physical education classes43,44 are effective preventive measures. In the two studies that reported changes in the body-mass index, in children in the treatment group, the body-mass index increased at an annualized rate of about 0.8 to 1.3 units less than in the children in the control group.41,43
Observational studies suggest that breast-feeding may be another preventive strategy.45 Both breast-feeding and later physical activity46 have been associated with reduced weight gain or the prevention of weight-related coexisting illnesses; both are generally safe and have other benefits that warrant their implementation. Other strategies that appear promising but have not been tested in randomized trials include the reduced consumption of sugar-sweetened beverages,47 reduced portion sizes at mealtimes,48 and increased consumption of fruits and vegetables.49
Areas of Uncertainty
Data from randomized trials to support any particular strategy over others to achieve weight control in children and adolescents28 or to prevent the development of overweight50 are currently lacking. The approaches outlined above apply to children and adolescents who are mildly to moderately overweight. Patients for whom treatment is the most challenging are those who are severely overweight (with a body-mass index of 40 or more); these patients may benefit from treatment by providers with experience in the management of such cases. Aggressive approaches to treatment for severely overweight patients include drug therapy, restrictive carbohydrate-free, hypocaloric diets, and bariatric surgery. Each of these should be considered only after more conservative approaches fail.
The two drugs currently approved for the management of obesity are sibutramine, an inhibitor of norepinephrine, serotonin, and dopamine reuptake, and orlistat, a lipase inhibitor that inhibits the absorption of dietary fats. The safety and efficacy of sibutramine have not been established for patients less than 16 years of age, and orlistat has not been evaluated in patients less than 12 years of age. A six-month clinical trial of sibutramine in adolescents demonstrated that patients who were treated with this agent lost 4.6 kg more weight than did patients who received placebo.51 A 54-week clinical trial of orlistat in adolescents, as described in the package insert, found a significantly greater reduction in body-mass index among patients treated with orlistat than among those who received placebo. As with other chronic diseases, weight maintenance is likely to require ongoing drug therapy. As the authors of the sibutramine trial concluded, "Until more extensive safety and efficacy data are available, medications for weight loss should be used only on an experimental basis in adolescents and children."51
Hypocaloric diets containing less than 20 g of carbohydrate result in rapid weight loss and appear to block hunger.52 Their use in pediatric patients has been described52 but requires physician oversight and monitoring. There have been limited published reports of experience with bariatric surgery in the pediatric age group. Available recommendations suggest the limitation of its use to adolescents with a body-mass index of 40 or more who also have obesity-associated coexisting illnesses; the recommendations also specify criteria for referral and treatment.53
Guidelines
An expert committee that included representatives from the American Academy of Pediatrics, the American Dietetic Association, and the National Association of Pediatric Nurse Practitioners has issued consensus recommendations for the assessment and treatment of childhood and adolescent overweight.23 Consensus recommendations for the use of bariatric surgery in adolescents have also been published53 and endorsed by the American Pediatric Surgical Association.54 The recommendations of these organizations agree with those outlined here.
Summary and Recommendations
Several strategies are useful in the management of overweight patients who are seen in primary care settings, such as the seven-year-old girl described in the vignette. The routine assessment of body-mass index will allow providers to identify modest excesses of weight when the behaviors that contribute to them are tractable. Communication strategies that avoid blame and encourage concern and an interest in change on the part of overweight patients and their families are critical to management. Most causes and complications of overweight can be identified by medical history and physical examination. A fasting lipid profile is a reasonable test for all overweight children. The medical history (with attention to risk factors for diabetes or other complications), the physical examination (to rule out such conditions as acanthosis nigricans), and the likelihood that test results will affect the management of the case should guide further testing. Treatment should focus on habits of diet or activity that contribute to weight gain or impair weight loss and that can be modified; recommendations should be based on a sensitivity to competing family priorities, particularly in the absence of apparent complications of overweight. Relevant behaviors should be quantified to facilitate monitoring and change, and positive changes should be reinforced. In the case vignette, immediate targets for change suggested by the history include a reduction in the intake of soft drinks and in screen time and an increase in active play. Our initial goal for this patient would be to maintain her current weight for one year and to achieve a body-mass index that is below the 85th percentile for her age, assuming that she undergoes continued linear growth at the 90th percentile. We would recommend weekly to monthly face-to-face or telephone monitoring of behavioral and weight goals by the primary care provider. In some settings, nurses, dietitians, or other health professionals may help accomplish frequent follow-up assessments.
We are indebted to Barbara Polhamus for her assistance.
Source Information
From the Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, Atlanta (W.H.D.); and the Division of General Pediatrics and Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, Calif. (T.N.R.).
Address reprint requests to Dr. Dietz at the Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, 4770 Buford Hwy. NE, MS K-24, Atlanta, GA 30341, or at wcd4@cdc.gov.
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