Summary of Recommendation and Evidence

The U.S. Preventive Services Task Force (USPSTF) recommends screening all adults for obesity. Clinicians should offer or refer patients with a body mass index (BMI) of 30 kg per m² or higher to intensive, multicomponent behavioral interventions (Table 1). B recommendation.

Rationale

Importance. The prevalence of obesity in the United States is high, exceeding 30 percent in adult men and women. Obesity is associated with such health problems as an increased risk of coronary heart disease, type 2 diabetes mellitus, various types of cancer, gallstones, and disability. These comorbid medical conditions are associated with higher use of health care services and costs among obese patients.

Obesity is also associated with an increased risk of death, particularly in adults younger than 65 years. The leading causes of death in obese adults include ischemic heart disease, diabetes, respiratory diseases, and cancer (e.g., liver, kidney, breast, endometrial, prostate, colon). Weight loss in obese individuals is associated with a lower incidence of health problems and death.

Detection. BMI is calculated from the measured weight and height of an individual. Recent evidence suggests that waist circumference may be an acceptable alternative to BMI measurement in some patient subpopulations. Screening tests were not a specific focus of this review.

Benefits of detection and early intervention. The USPSTF found adequate evidence that intensive, multicomponent behavioral interventions for obese adults can lead to an average weight loss of 4 to 7 kg (8.8 to 15.4 lb). These interventions also improve glucose tolerance and other physiologic risk factors for cardiovascular disease.

The USPSTF found inadequate direct evidence about the effectiveness of these interventions on long-term health outcomes (e.g., death, cardiovascular disease, hospitalizations).

Harms of detection and early intervention. Adequate evidence indicates that the harms of screening and providing behavioral interventions for obesity are no greater than small.

USPSTF assessment. The USPSTF concludes with moderate certainty that screening for obesity in adults has a moderate net benefit. There is also benefit to offering or referring obese adults to intensive behavioral interventions to improve weight status and other risk factors for important health outcomes.

Clinical Considerations

Patient population. This recommendation applies to adults 18 years or older. The USPSTF uses the following terms to define categories of increased BMI: overweight is defined as a BMI of 25 to 29.9 kg per m², and obesity is defined as a BMI of 30 kg per m² or greater.

Interventions. The USPSTF found that the most effective interventions were comprehensive and were of high intensity (12 to 26 sessions in a year). Although the USPSTF could not determine the effectiveness of other specific intervention components, most of the higher-intensity behavioral interventions included multiple behavioral management activities, such as group sessions, individual sessions, setting weight-loss goals, improving diet or nutrition, physical activity sessions, addressing barriers to change, active use of self-monitoring, and strategizing how to maintain lifestyle changes.

Weight-loss outcomes improved when interventions involved more sessions (12 to 26 sessions in the first year). Behavioral intervention participants lost an average of 6 percent of their baseline weight (4 to 7 kg) in the first year with 12 to 26 treatment sessions compared with little or no weight loss in the control group participants. A weight loss of 5 percent is considered clinically important by the U.S. Food and Drug Administration (FDA).

For obese patients with elevated plasma glucose levels, behavioral interventions decreased the incidence of diabetes diagnosis by about 50 percent over two to three years (number needed to treat = 7). Behavioral interventions also demonstrated some improvement in intermediate health outcomes, such as blood pressure, waist circumference, and glucose tolerance.

Interventions that combine pharmacologic agents (orlistat or metformin) with behavioral interventions resulted in weight loss and improvement in physiologic outcomes. Orlistat led to an average weight loss of about 2.6 kg (5.7 lb), a decrease in waist circumference of 1.9 cm, and a decrease in fasting glucose level. However, there are concerns about the potential harms of orlistat because of recent FDA reports of rare severe liver disease and a lack of long-term safety data.¹ Metformin led to a 1.5-cm greater decrease in waist circumference; however, its use for obesity is not approved by the FDA and is thus considered an off-label use. In addition, sufficient data were lacking about the maintenance of improvement after discontinuation of medications. As a result, the USPSTF is unable to recommend medication use.

Results of trials were not stratified by BMI category, making it difficult to ascertain the certainty of benefit in overweight groups (BMI of 25 to 29.9 kg per m²). Although some studies included overweight participants, the mean BMI across trials was in the obese range (30 kg per m² or greater). Therefore, the USPSTF was unable to examine differential effects of interventions on both overweight and obese patients. However, the recommended interventions may also lead to weight loss in some overweight patients. Compared with that of obesity, less is known about the association of overweight and long-term health outcomes.

Screening intervals. No evidence was found about appropriate intervals for screening.