July 2008
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Multimodal Childhood Obesity Treatment Programs: An Evidence-Based Review
By Sarah Armstrong, MD
Childhood obesity is one of the most serious health problems facing children today. Despite recent data suggesting a plateau in rates of childhood obesity in the last 10 years,1 the prevalence of obesity has increased from 5.0% to 13.9% in children aged 2 to 5 years, from 6.5% to 18.8% in children aged 6 to 11 years, and from 5.0% to 17.4% in 12- to 19-year-olds, since 1974.2 Overweight children are likely to become overweight adults3,4 and are at increased risk of weight-related comorbidities such as hypertension, hyperlipidemia, and type 2 diabetes.5 These risk factors are predicted to cause coronary heart disease in up to 16% of 35-year-old adults by the year 2035 if current trends continue.6
TREATMENT OF CHILDHOOD OBESITY
The treatment of overweight and obese children and adolescents has been frustratingly difficult, time consuming, and expensive.7 Lifestyle intervention in the form of dietary and exercise counseling remains the foundation of obesity care; however, it is difficult to implement effective, economically feasible solutions with demonstrated benefit. Pharmacotherapy and bariatric surgery protocols are emerging, but these remain options for a small number of significantly obese children. The need for evidence-based programs with proven health outcomes is apparent.
The American Medical Association, with the support of the American Academy of Pediatrics (AAP), the American Dietetic Association, the American Heart Association, and the Endocrine Society, recently released Expert Panel Recommendations for the prevention, assessment, and treatment of overweight and obese children in the office setting.8 This guide, published in the December 2007 supplement to Pediatrics, is an update to the 1998 recommendations.
The tertiary care, multimodal approach to obesity treatment is a nationally emerging trend. The advantages include the proximity of multiple pediatric subspecialists, existing infrastructure to systematically evaluate outcomes, and an established patient-referral base. This evidence-based review summarizes factors that should be considered when devising treatment goals, target outcomes, types of expertise necessary, and specific diets or exercise plans. Due to the difficulty in comparing methodologies across unique and individual approaches to the problem, this review combines data published from both hospital-based and nonhospital-based settings.
TREATMENT GOALS, TARGET OUTCOMES
The primary goals of obesity treatment are (1) resolution of acute and chronic complications including dyslipidemia, hypertension, hepatic dysfunction, and glucose intolerance; (2) reduction of risk for acute and chronic disease through decreases in adiposity; (3) improving quality of life; and (4) improving overall physical health through permanent lifestyle modifications.9 These goals should be quantified and measurable, and should be tracked and reviewed at regular intervals.
Weight, adiposity, and body mass index. Quantifying a decrease in adiposity remains a challenge. Depending on age and gender, an individual child's body mass index (BMI) may be expected to increase, decrease, or stay the same with normal development. Overweight, or BMI between the 85th and 94th percentile, denotes both those children with excess body fat as well as some with excess lean body mass and minimal risk. Obesity, or BMI >95th percentile, is much more likely to denote excess body fat and therefore increased risk.10,11 A third category, ≥99th percentile reflects a category of risk above that represented by the obese category. This 99th percentile cutoff line does not currently exist on the standard BMI growth chart but is available as a separate table (Table 1). Specific BMI goals vary depending on age, stage of pubertal development, degree of obesity, and existing comorbidities (Table 2).7 In general, the goal is for the BMI to deflect downward until it reaches the 85th percentile or below. Even lesser reductions in body weight (5%–10%) may improve metabolic function and reduce the risks of complications, at least in obese adults.12
Due to the challenges inherent in using pediatric BMI as a sole outcome measure, many studies have used a decrease in BMI z-score or BMI percentile as a surrogate measure for decreased adiposity. There are currently no standards for the definition of a successful intervention by BMI-related measures. Paluch et al have published a review on existing definitions of success and proposed a unique measure termed percent over BMI. The percent over BMI describes the percent greater than the 50th percentile BMI for age and gender ([BMI – BMI at 50th percentile/BMI at 50th percentile] X 100).13
Additional studied measures of adiposity in children or adults include waist circumference, abdominal circumference, waist-to-hip ratio, skinfold thickness, bioimpedance, or other measures of body fat percent. Two reference tables standardize abdominal circumference by race, gender, and age in white and black children aged 5 to 17 years. The table by Tayor et al is more sensitive, and the tables by Freeman et al are more specific.14 Limitations of these tables include lack of diversity of sample population and lack of interrater reliability performing the measurement. Therefore, these surrogate markers are not currently recommended for clinical purposes.7
IMPROVING PSYCHOSOCIAL OUTCOMES
A successful treatment program helps the child and family develop healthy relationships with food and body. Excessive negative attention to weight may cause serious harm and may lead to the development of disordered eating patterns. Examples of potentially harmful approaches include setting unrealistic expectations, giving overly restrictive advice, using exercise as a punishment or failing to consider sustainability, and focusing only on the overweight child rather than the family unit.15 One study of obesity treatment reports higher rates at 10-year follow-up of psychiatric disorders such as depression, substance abuse, and eating disorders.16 Other studies have reported improvement in children's psychosocial functioning and did not detect higher rates of eating-disordered behavior.17,18
Behavioral and mental health status can be assessed by the routine use of standardized, quantitative questionnaires. Currently, no validated screens exist that can quickly evaluate both nutrition and activity in children. Several questionnaires evaluate lifestyle factors, and others screen for anxiety, depression, and other mental health indicators. Behavioral screening tools should be administered at enrollment and periodically throughout the intervention.
RISK REDUCTION
A successful program will quantify direct improvement in cardiovascular and metabolic status. Frequent measurements of blood pressure, fasting lipids, glucose, or other chosen laboratory tests can demonstrate health status improvement over time. According to the AAP Expert Panel Report, a standard set of screening labs should be measured at specified intervals in overweight children aged more than 2 years. For children with a BMI >85th percentile and no risk factors, a fasting lipid panel is indicated. For overweight children older than 10 years with risk factors or any child with BMI > 95th percentile, this also includes a fasting glucose and ALT/AST biannually. Children with abnormal test results should be retested every 6 to 12 months.7
MULTIDISCIPLINARY TEAM COMPONENTS
The AAP Expert Panel recommends that a tertiary care obesity treatment center should offer "continued diet and activity counseling plus consideration of meal replacement, very low-energy diet, medication, and surgery." In addition, pediatric weight-management centers should operate under established clinical or research protocols to track trends, adverse events, and outcomes. The treatment team should be multidisciplinary and comprise professionals with expertise in childhood obesity, behavioral counseling, dietary, and exercise counseling. A medical professional trained in endocrinology, gastroenterology, cardiology, or bariatric medicine can provide clinical oversight and comorbidity screening.7 Simply providing education about what changes are indicated is ineffective.19
Although existing obesity treatment programs vary, most offer a combination of dietary modification, fitness training, and behavioral therapy. The effectiveness of these comprehensive programs is difficult to compare due to differences in type and intensity of intervention components, location of services provided, types of providers, dietary strategies employed, and demographics of participants. Combined approaches appear to be more successful in achieving improved weight status and health outcomes than programs that target one component in isolation.20
NUTRITIONAL INTERVENTION
To date, no clinical trials have shown that dietary modifications alone are effective long-term in reducing rates of overweight in children.7 There is, however, evidence supporting several dietary recommendations (Table 3). Dietary approaches that have been studied include low-calorie diets, low-carbohydrate/protein-sparing diets, low-glycemic-index (GI) diets, and the "traffic light" diet.
As part of a multidisciplinary program, a low-calorie diet may be effective in children aged 6 to 12 years.7 Low-calorie is defined differently in various studies, but in general should be fewer calories than required for weight maintenance but not less than 900 kcal, preferably 1,200 kcal/day. Of the six studies on low-calorie diets, four reported improvement in at least one measure of adiposity, and two reported weight gain.7
There are no long-term safety or efficacy data for low-carbohydrate diets in children.21 In adults, weight loss has been achieved for 3 to 6 months, but there is limited evidence for efficacy beyond 1 year. The best reported weight-loss data show <5% total body mass lost after 18 months.22 Given the absence of safety data for low-carbohydrate intake during periods of growth and development, this approach cannot currently be recommended.
Foods that have a low GI cause the blood sugar to rise less quickly than foods with a high GI. The value is calculated as the area under the glucose response curve after consumption of 50 g of carbohydrate from test food versus glucose. High-GI foods are ≥70, moderate-GI foods are 56 to 69, and low-GI foods are ≤55. Two studies, one in children and one in adult women, found that patients assigned to a low-GI diet lost more weight than those on a low-fat diet.23,24 Other studies have shown no effect.25
The best evidence for a specific dietary prescription is Epstein's traffic light diet. This diet is part of a comprehensive intervention aimed at children aged 6 to 12 years and their families. The core concept is to provide a simple, low-calorie diet (900–1,500 kcal/day). Food groups are divided into three categories: green (low energy, nutrient-dense), yellow (moderate energy), and red (nutrient poor, energy dense) and can be consumed in relative quantities.26,27 This approach demonstrated modest sustained weight loss at 5 and 10 years. Whether or not this outcome is possible to replicate in the general population is unclear because the study was limited in scope to primarily white, upper middle-class families.28
ACTIVITY INTERVENTION
Studies show that an increase in sedentary activities such as television viewing and a decrease in physical activity contribute to the national increase in prevalence of childhood obesity.29 One study showed that an increase in physical activity by 60 minutes a day is associated with a BMI decrease of 0.06 kg/m² in girls and 0.22 kg/m² in boys.30 Another study demonstrated a direct correlation between higher self-reported activity levels and lower BMI.31 The AAP32 and the US Department of Agriculture33 recommend that all children get at least 60 minutes of active time per day.
In a multimodal setting, there are many options for increasing physical activity. Some centers provide fitness testing onsite; some include an assessment of fitness level but do not provide actual activity time, and some contract with local YMCAs or other fitness facilities to provide structured activity. It is important to identify and overcome barriers such as lack of school-based physical education, perceived neighborhood safety, and excessive sedentary activities. Gortmaker et al demonstrated that a reduction in BMI could be achieved through reduction of television viewing time in 1-hour increments.34 Robinson et al showed a statistically significant reduction of BMI with reduction in television viewing and eating meals while watching television.35
BEHAVIORAL INTERVENTIONS
Many variations exist on the behavioral treatment model for childhood obesity. Some programs utilize group-based treatments, while others offer individual counseling to patients or families. Group-based treatments may be more cost-effective and have therapeutic benefit.36,37 Several studies have demonstrated the importance of parental involvement in childhood weight-management programs.38,39 In two clinical studies, targeting the parents alone as the exclusive agents of change was more effective in achieving changes in the child's BMI than was targeting either the children alone or the child and parent together.40
Programs also vary in frequency of patient contact and duration. These range from contact every week to every 6 months for a total of 6 weeks to 1 year. There are no data that define the optimal interval between visits, frequency, or duration; however, the best data available come from weekly sessions that last 8 to 12 weeks, with maintenance visits thereafter.8
The routine assessment of eating-related disorders and abnormal eating behaviors should be a part of any behavioral treatment program. The Youth Risk Behavior Surveillance Survey indicates that 15% of all teens practice some form of disordered eating.41 These behaviors include sneaking food, emotional eating, breakfast-skipping, excessive eating out, and over-frequent snacking.
Family- and patient-centered interviewing styles have superior efficacy to the traditional prescriptive approach commonly used in other areas of medicine. The theory behind Motivational Interviewing (MI) is that a clinician's instruction to change a behavior will only be effective if family members recognize a problem, have personal interests in that problem, and are confident that they can change the problem.42 Providers can complete training in MI through a national training network.43 Schwartz et al demonstrated that the use of 15-minute MI sessions in an outpatient setting decreased BMI in children over a 6-month period.44
CONCLUSIONS
There are no ironclad standards for the design and structure of a multimodal childhood obesity treatment center. This leaves open many possibilities for the academic pediatrician who wishes to provide treatment options for overweight and obese children and their families. Nevertheless, any program should be comprehensive in scope and should encompass medical, dietary, behavioral, and fitness evaluation and various forms of treatment. Available evidence supports the use of parent- or family-centered programs, group settings, frequent, regular contact, and dietary and fitness advice based on specific goals. To improve services, methods of program evaluation and patient feedback should be incorporated. Much work is needed to establish the optimal design of such programs; however the growing epidemic of obesity and related health problems mandate our continued efforts.
Sarah Armstrong, MD, is the Medical Director of the Healthy Lifestyles Program, in the Division of Pediatric Primary Care at Duke University Medical Center, Durham, NC. She may be reached at sarah.c.armstrong@duke.edu; phone: 919-620-5315; or fax: 919-471-6390.
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