Journal Issue: Childhood Obesity Volume 16 Number 1 Spring 2006
Current Specialized Treatment Programs and Interventions
Surprisingly little evidence-based, high-quality research exists on interventions to treat childhood obesity. A summary of the research behind obesity interventions for both adults and children was published in April 2004 in the British Medical Journal.26
Most of the effective treatment programs have been carried out in academic centers through an interdisciplinary approach that combines a dietary component, behavioral modification, physical activity, and parental involvement.27 L. H. Epstein and his team at the State University of New York at Buffalo have been in the forefront of developing programs that reduce adiposity in childhood through this multidisciplinary approach. The most important finding of these interventions may be that relatively modest but sustainable changes in lifestyles may have more long-term impact on obesity than radical regimens that enable patients to lose weight rapidly but not to maintain their new, lower weight afterward. In perhaps the only successful long-term intervention, Epstein used such behavioral strategies as contracting, self-monitoring, and social reinforcement with obese children and their parents to limit consumption of fatty foods and to increase exercise.28 Although research has demonstrated that intensive group programs can be successful, such programs have yet to be translated to primary care centers. In the absence of well-established, office-based evaluation and treatment programs, the Maternal and Child Health Bureau and the National Center for Education in Maternal and Child Health have issued recommendations for the obese child's evaluation and treatment that are strongly based on comprehensive interventions like those Epstein developed.
Dietary Components of Treatment
Most lifestyle intervention programs in children use a diet that mildly restricts calories. The classic example is the Traffic Light Diet, which color-codes foods as green, yellow, and red to signal whether they are safe to eat in any quantity (green), require moderation and caution (yellow), or should generally be avoided (red). Combining comprehensive obesity-treatment programs with the Traffic Light Diet can significantly change eating patterns.29 Indeed, one study found that the diet continued to affect the eating habits of children five to ten years after treatment began.30 Diets more restricted in calories, including high-protein diets, are used rarely and only in more severe forms of obesity. Given their potential danger, they should be implemented under strict medical control, possibly in a clinical setting.
Interest is also growing in whether low-carbohydrate diets can help reduce adiposity in adults.31 A recent study showed that obese men and women lost more weight and had more significant reductions in plasma triglyceride concentrations on a low-carbohydrate diet than on conventional low-fat diets.32 And limited evidence suggests that the nature or quality of ingested carbohydrates may modulate weight gain in childhood. Although the relationship between carbohydrates and weight gain is still highly controversial, studies by D. Ludwig and several colleagues strongly link consumption of sugar-sweetened drinks with obesity.33 Thus emerging data would suggest that eliminating carbonated drinks or other sugary drinks from the diet can significantly reduce caloric intake and obesity.34 But low-carbohydrate diets should not be used for children and adolescents until more information is available regarding their effects on insulin resistance and their long-term effects on weight and metabolic health.
Role of Physical Exercise
Physical activity is a critical component of obesity treatment in both adults and children. Increasing the caloric expenditure of obese children may not only accelerate their weight loss, but also make it easier to maintain weight changes. Exercise in the absence of dietary intervention, however, has not been found to affect weight significantly. And for the obese child, exercising can be difficult. Few studies have explored the effects of aerobic exercise on children's body weight and cardiovascular fitness. Nor is much information available regarding the effects of resistance exercise on children's metabolism and body weight. But because the capacity for voluntary exercise declines with the increasing severity of obesity, resistance exercise may prove more effective than more strenuous aerobic exercise. As yet there are no evidence-based guidelines by which to design exercise programs for obese children. Epstein and his team have suggested reducing sedentary behaviors as an alternative to increasing physical activity, an interesting approach that may be helpful both in treating and in preventing obesity. Inactivity can be decreased in many ways, usually most successfully when a parent is involved. The best example is reducing the time that the child spends watching television.35
Pharmacologic Approaches in Pediatrics
Many experts in pediatric obesity argue that behavioral treatment alone is ineffective, particularly in the case of severe obesity. Few if any guidelines exist for using medications in treating child obesity. In general, however, experts suggest that children and adolescents with a BMI greater than the 95th percentile for age and sex and with obesity-related medical complications that may be corrected or improved through weight reduction should be considered for intensive regimens, including medication.36 Most medications approved for weight loss in the United States either suppress appetite or reduce nutrient absorption. A third emerging therapy is not aimed directly at controlling weight but rather targets insulin resistance to reduce the metabolic complications associated with obesity.
The Food and Drug Administration (FDA) approved sibutramine (Meridia), an appetite suppressant, for weight loss and maintenance in conjunction with reduced caloric intake in adults and adolescents older than age sixteen.37 R. I. Berkowitz and several colleagues provided the first randomized, placebo-controlled trial of sibutramine in treating obese adolescents.38 The double-blind study followed eighty-two adolescents with a BMI of 32 to 44 for six months, and then all patients received the drug without being blind to the treatment for another six months. Including sibutramine as part of a comprehensive behavioral program resulted in greater weight loss in obese adolescents than the traditional behavioral treatment alone, but the weight loss plateaued after six months of therapy. Serious side effects, such as hypertension and tachycardia (rapid heart rate), were reported in nineteen out of forty-three youngsters; in five, the drug dose had to be reduced or discontinued. The study found no major improvement in insulin resistance and dyslipidemia. A. Matos-Godoy and several colleagues also evaluated the efficacy and safety of sibutramine in a six-month double-blind, placebo-controlled trial in sixty obese adolescents.39 Unlike the Berkowitz study, it found no clinically significant changes in blood pressure.40 Both studies concluded that sibutramine should be used for weight loss in adolescents and children only on an experimental basis until more extensive safety and efficacy data are available.
In future tests of sibutramine in children and adolescents with severe obesity, researchers could experiment with different strategies. For example, introducing the drug after a period of weight reduction with traditional approaches may reduce the potential for such side effects as hypertension.
Orlistat (Xenical), a drug that decreases nutrient absorption, cuts intestinal fat absorption by up to 30 percent. The FDA approved its use in children older than age twelve. A multicenter, one-year randomized, placebo-controlled trial in 539 obese adolescents found that those who used orlistat lost weight and had significantly greater reductions in BMI and body fat than those given the placebo.41 But the two groups saw no significant differences with respect to changes in lipid or glucose levels. The explanation for the failure of lipid and glucose levels to improve may be that the body weight loss was small (5 percent). Although researchers do not yet know how much BMI must be reduced to provide short- and long-term health benefits in children and adolescents, the above study would suggest that small changes in weight do not affect the metabolic risk factors.
The third class of drugs used in treating obesity are those that target insulin resistance, which, along with the associated high insulin levels, are often present in obese children and adolescents and which vary with the degree and severity of overweight. Both disorders may not only contribute to the metabolic complications of obesity but also accentuate weight gain in children and adolescents by promoting lipid storage. Thus targeting insulin resistance may have a dual effect—preventing further weight gain and improving the associated metabolic complications. Metformin, for example, is used in treating type 2 diabetes.42 It is approved for adolescents. Only two small studies have used metformin in a randomized trial in obese adolescents.43 Both found small but statistically significant effects on BMI and significant effects on fasting blood sugar, insulin, and lipids. The studies are encouraging and should be repeated in a larger sample and for a longer duration.
When possible, it is always best to treat obesity without using drugs. Unfortunately, however, once both adult and child patients have lost weight, their efforts to maintain their new weight often fail. That so many people regain weight after stopping medication clearly suggests that obesity is a chronic condition that requires continuous treatment. And even though environmental factors have played an important role in childhood obesity's dramatic rise over the past two decades, clearly there is a genetic component to body weight. Indeed, recent data suggest that 5 percent of cases of severe obesity in children younger than ten are due to genetic mutations.44 These children and adolescents need multiple strategies, including drugs, used in combination in a carefully designed treatment program.
Research over the past decade has dramatically advanced knowledge about the molecular mechanisms regulating body fat and the central regulation of energy intake. Ultimately, for the severe forms of obesity, the future lies in developing new and more effective medications. Researchers should continue to investigate the causes of childhood obesity and to refine obesity's classifications and diagnoses based on health risks.
Surgery is used to treat obesity in adults only when patients are severely obese (or their BMI greater than 40) or when they have a BMI greater than 35 together with severe obesity-related health complications. In the Swedish Obese Subjects (SOS) Study, a large study evaluating surgery's efficacy, patients were equally divided among surgical and nonsurgical groups.45 After two years, the surgical patients had lost 28 kilograms (62 pounds); those in the control group, 0.5 kilograms. After eight years, the average weight loss was 20 kilograms in surgical patients and 0.7 kilograms in controls. Thus overall, surgery promoted substantial, prolonged weight loss in patients with severe obesity.46 Results in the relatively few published surgical trials in obese children and adolescents seem to parallel those of adult trials.47 Nevertheless, evidence-based guidelines should be developed for surgery as a treatment of childhood obesity.
Primary and Specialized Care
Chronically obese children are increasingly being referred to pediatric endocrinology centers, often years after the onset of obesity. A study by T. Quattrin and several colleagues found that most of the children who were referred to specialists had developed obesity in their preschool years, when preventive measures are likely to be most effective, if implemented. Two years after the first visit to the specialist, only 38 percent of the children were less overweight than they were on their first visit.48 The study concluded that such referrals are ineffective, and efforts should go, instead, to developing and making available to pediatricians early family-based, behavioral lifestyle intervention programs. The study's primary point, however, was not to address where the child should receive care but to emphasize that effectively treating obesity in children and adolescents requires a well-designed, multifaceted intervention program. Given the chronic nature of obesity, frequent visits for treatment are indispensable. The traditional, sporadic, every-six-months visit that a normal primary care practice provides is not adequate. Because many obese children and adolescents also suffer from one or more metabolic complications, the role of the pediatric endocrinologist is critical in the multidisciplinary approach to the problem. Both pediatricians and patients must realize that the goal of treatment is not the initial weight loss alone but also weight management to achieve the best possible weight for improved health. The growing prevalence of childhood obesity indicates an urgent need to develop effective strategies for prevention and treatment.