Childhood Obesity, Part 2: Is There Effective Treatment?
ABSTRACT: Lifestyle interventions form the cornerstone of obesity treatment. Successful weight management programs involve the family and include frequent visits (2 per week) over several months with ongoing maintenance visits. Low glycemic index and low glycemic load diets are effective for many patients. Increased physical activity has a clear beneficial effect on insulin sensitivity, even in the absence of weight loss. Encouraging participation in organized sports or activities may help children become more active. For adolescents with a body mass index above the 95th percentile in whom lifestyle interventions have failed, orlistat (for patients 12 years and older) or sibutramine (for patients 16 years and older) can be considered in combination with a low-calorie diet.
Key words:
childhood obesity, body mass index, type 2 diabetes mellitus
Increased weight in children is associated with many comorbidities, including hyperlipidemia, hypertension, hepatic steatosis, polycystic ovary syndrome, and insulin resistance. Type 2 diabetes mellitus, in particular, represents a major new health issue for obese adolescents.1-3 Obesity in childhood also augurs health problems later in life.
Recently, increased childhood body mass indices (BMIs) (above the 95th percentile) have been associated with increased cardiovascular risk in adulthood. 4 These data underscore the importance of obesity screening, prevention, and treatment in children and adolescents. In this article, I provide an overview of obesity interventions. In a previous article (Childhood Obesity, Part 1: Weight Evaluation and Comorbidity Screening), I reviewed how to screen children for obesity and when to screen for comorbidities associated with obesity.
OBESITY INTERVENTION
Overweight and obese patients. Patients with a BMI higher than the 85th percentile require lifestyle counseling. Laboratory evaluation with fasting blood glucose measurements, lipid panel, and liver function tests is indicated for patients with abnormal physical findings (eg, acanthosis nigricans), a high-risk family history (eg, type 2 diabetes), and for those who continue to gain weight despite lifestyle counseling. Positive laboratory results signal the need for a structured weight loss program, including a tailored diet and exercise versus sedentary activity evaluation.
The focus at this stage is on risk factor reduction. Medications for associated conditions and possibly weight loss medications may be considered. Patients with hyperlipidemia. The new lipid screening guidelines from the American Academy of Pediatrics Committee on Nutrition recommend dietary changes and other lifestyle interventions, such as increased physical activity, for children with elevated low-density lipoprotein (LDL) cholesterol levels and in- creased cardiovascular risk.5
Consideration of pharmacological interventions is recommended for those 8 years and older whose LDL cholesterol level is higher than 190 mg/dL (or higher than 160 mg/dL with a family history of early heart disease or at least 2 additional risk factors, or higher than 130 mg/dL when diabetes is present).
LIFESTYLE CHANGES
The cornerstone of both obesity prevention and treatment is lifestyle intervention. Weight management programs that involve the family and include frequent visits (2 per week) over several months with ongoing maintenance visits are associated with successful weight loss.6 One study showed that after 6 months, this regimen resulted in a 2.6% decrease in weight in the intervention group, compared with a 5.04% increase in weight in the control group.7
Dietary instruction. Low glycemic load and low glycemic index diets have been effective for weight reduction in obese adolescents and children.8,9 Low glycemic diets must be differentiated from very low carbohydrate diets. “Very low carbohydrate” refers to the total carbohydrate content of a diet relative to total calories. The glycemic index of a food indicates the extent to which a set amount (by weight) of the food will raise the blood glucose level, compared with the same amount of a criterion food (glucose or white bread).
The glycemic load of a food is calculated by multiplying the glycemic index of the food by the carbohydrate content of a single portion. In many studies, low glycemic load diets have resulted in more rapid initial weight loss (within the first 6 months) compared with higher glycemic load diets.10 Very low carbohydrate/high-fat diets and lowfat/ high-carbohydrate diets of equal caloric content have resulted in equal weight loss in the long term (1 year or longer).11
Lipid profiles have varied among the adherents of different types of diets. For patients with hypercholesterolemia and elevated LDL cholesterol levels, a low-fat/high-carbohydrate diet seems best12; however, low glycemic index diets have also resulted in improved cholesterol and LDL levels in this population.13 There is a consensus that low glycemic diets are beneficial for persons with prediabetes and diabetes.14 A key component of the effectiveness of any diet is the extent to which a patient adheres to it. Tips for encouraging children to make better food choices are listed in Table 1. Exercise. Increased physical activity has been clearly shown to have a beneficial effect on insulin sensitivity even in the absence of weight loss,15 whereas a highly sedentary lifestyle is associated with not only increased weight16 but also insulin resistance.
Physical activity recommendations for children are listed in Table 2. One study with middle school–aged children documented that the use of a pedometer in conjunction with reinforcement in the form of television viewing(the number of hours allowed determined by the number of steps accumulated) was highly successful in increasing physical activity and reducing television viewing compared to simple use of the pedometer alone.17
PHARMACOLOGICAL THERAPY
No weight-loss medications are approved for use in children younger than 12 years. The 2 weight-loss medications approved for use in adolescents are orlistat (marketed as Xenical in prescription format and Alli as an over-the-counter product) and sibutramine (marketed as Meridia). Use of these agents is reserved for those patients who are obese (BMI at the 95th percentile or higher)—especially those with obesity-related comorbidities— and in whom lifestyle interventions for a minimum of 6 months have failed.18 Weight-loss medications should be used in combination with a low-calorie diet.
Orlistat is approved for patients 12 years and older. This GI lipase inhibitor blocks fat absorption. It resulted in an average decrease in BMI equal to 0.55 kg/m2 in a multicenter, placebo-controlled, randomized study of 12- to 16-year-olds.19 Orlistat must be taken with each meal that contains fat; however, it should not be taken at the same time as vitamin supplements because of the risk of fat-soluble vitamin malabsorption. Other adverse effects include flatulence, crampy abdominal pain, oily staining, and diarrhea. Sibutramine is approved for patients 16 years and older. This norepinephrine and serotonin reuptake inhibitor decreases appetite and may also increase food-induced thermogenesis.
Adverse effects include tachycardia and elevation of blood pressure. In a randomized placebocontrolled trial, sibutramine resulted in an average decrease in BMI equal to 2.9 kg/m2 over 12 months.20 Metformin is approved for the treatment of diabetes in children 8 years and older. In a number of small studies of obese children without diabetes, metformin resulted in an average decrease in BMI of 0.5 kg/m2 as well as a decrease in the fasting glucose level.21 Thus, metformin has been widely used to facilitate weight loss in patients with manifestations of insulin resistance,21-24 although it does not have an FDA indication for this. Suppression of hepatic glucose production is considered the primary mechanism of action of metformin.
Adverse effects, including crampy abdominal pain and diarrhea, are usually mild with a graded dosage increase over 1 to 2 weeks; they diminish with duration of use.
SURGERY
The 2 procedures commonly used to treat obesity, laparoscopic gastric banding (LAGB) and rouxeny gastric bypass (RYGB), are under investigation in severely obese adolescents (BMI of 40 kg/m2 or higher). RYGB combines both restriction and malabsorption to achieve weight loss, whereas LAGB is purely restrictive. In adults, RYGB resulted in weight loss of about 40 kg that was maintained for more than 36 months; after surgery about 17% of patients reported nutritional and electrolyte abnormalities and 18% had surgeryrelated adverse events.25 Mortality after RYGB averages 1%, compared with 0.4% after LAGB.25 LAGB has resulted in weight loss of about 33 kg at more than 36 months.
Adverse events associated with LAGB have been fewer and less severe; 7% were GI-related, and 13% were primarily surgery-related. A technical review for the State of Washington documented that 1 year after surgery, the strength of evidence is moderate that both LAGB and RYGB lead to significant and sustained weight loss in adolescents compared with nonsurgical approaches. 26 However, considerably less pediatric data are available on these procedures than on nonsurgical approaches. Currently, surgical interwww.ventions in adolescents may be considered for those with a BMI of 50 kg/m2 or higher or those with a BMI of 40 kg/m2 or higher who have comorbidities that may be relieved by weight loss.
In addition, surgical interventions should be reserved for adolescents who have not succeeded with lifestyle interventions and who can have the surgery as part of a comprehensive program with longterm follow-up monitoring.27
ARE OBESITY INTERVENTIONS EFFECTIVE?
Lifestyle and pharmacological interventions all show some degree of efficacy in adolescents28,29; however, the weight loss achieved is relatively small compared with the weight loss desired. Surgical interventions are gaining in popularity for severely obese adults and, more recently, adolescents, because of their ability to produce desired weight loss. It remains to be seen whether the associated surgical morbidity is minimal enough to recommend widespread use of such procedures.
Online Resources
Obesity http://www.ama-assn.org/ama/pub/category/11759.html
CDC Growth Charts: United States http://www.cdc.gov/nchs/about/major/nhanes/growthcharts/charts.htm
Health, Fitness, and Nutrition Physical Activity Guidelines for Americans http://www.health.gov/paguidelines/guidelines/default.aspx
The President’s Council on Physical Fitness and Sports http://www.fitness.gov
National Heart, Lung, and Blood Institute http://www.nhlbi.nih.gov/health/public/heart/obesity/wecan/
US Department of Agriculture http://www.mypyramid.gov
The President’s Challenge http://www.presidentschallenge.org higher).
RYGB combines both re striction and malabsorption to achieve weight loss, whereas LAGB is purely restrictive. In adults, RYGB resulted in weight loss of about 40 kg that was maintained for more than 36 months; after surgery about 17% of patients re ported nutritional and electrolyte ab normalities and 18% had surgery-related adverse events.25 Mortality after RYGB averages 1%, compared with 0.4% after LAGB.25 LAGB has resulted in weight loss of about 33 kg at more than 36 months.
Adverse events associated with LAGB have been fewer and less severe; 7% were GI-related, and 13% were primarily surgery-related. A technical review for the State of Washington documented that 1 year after surgery, the strength of ev idence is moderate that both LAGB and RYGB lead to significant and sustained weight loss in adolescents compared with nonsurgical approach es.26 However, considerably less pe diatric data are available on these procedures than on nonsurgical ap proaches. Currently, surgical interventions in adolescents may be con sidered for those with a BMI of 50 kg/m2 or higher or those with a BMI of 40 kg/m2 or higher who have co morbidities that may be relieved by weight loss.
In addition, surgical in terventions should be reserved for adolescents who have not succeeded with lifestyle interventions and who can have the surgery as part of a comprehensive program with long-term follow-up monitoring.27
ARE OBESITY INTERVENTIONS EFFECTIVE?
Lifestyle and pharmacological in terventions all show some degree of efficacy in adolescents28,29; however, the weight loss achieved is relatively small compared with the weight loss desired.
Surgical interventions are gaining in popularity for severely obese adults and, more recently, ado lescents, because of their ability to produce desired weight loss. It re mains to be seen whether the associ ated surgical morbidity is minimal enough to recommend widespread use of such procedures.