The prevalence of obesity among U.S. adolescents aged 12 to 18 years has risen to approximately 21%, according to a comprehensive review published in JAMA. The article by Kelly et al summarized current evidence on the epidemiology, pathophysiology, diagnosis, and treatment of adolescent obesity.

Key Findings

Obesity prevalence in U.S. adolescents increased from 16.0% during 1999 to 2002 to 20.9% during 2015 to 2018. Severe obesity, defined as a body mass index (BMI) ≥ 120% of the 95th percentile or BMI ≥ 35, increased from 5.3% to 7.6% among U.S. adolescents in the same period. New treatments, including pharmacotherapy and metabolic and bariatric surgery, show promising results in reducing BMI.

Comorbidities and Associated Risks

Compared to adolescents with overweight, those with severe obesity had a significantly higher prevalence of several cardiometabolic risk factors, including:

• High total cholesterol (19.4% vs 10.8%, P = .008)
• Low high-density lipoprotein cholesterol (23% vs 7.8%, P < .001)
• High triglyceride levels (29% vs 12.2%, P = .002)
• High systolic and diastolic blood pressure (3.8% vs 0.3%, P < .001)
• High glycated hemoglobin (24.3% vs 15.6%, P = .003).

Adolescents with obesity also had a higher risk of depression than healthy-weight peers (relative risk, 1.32; 95% confidence interval [CI], 1.09-1.60). Hypertension prevalence was higher in adolescents with obesity (31.4%) and overweight (18.2%) compared to healthy-weight peers (11.9%, P < .001). Obstructive sleep apnea was present in up to 60% of adolescents with obesity.

Eating disorders, particularly binge-eating disorder, were more prevalent in adolescents with obesity compared to healthy-weight peers (males: 9.3% vs 2.1%; females: 20.2% vs 8.4%).

Treatment Options

High-intensity interventions (26–51 contact hours over 3–12 months) demonstrated the greatest effect on BMI, with reductions of 3% to 5%. These interventions included nutrition and physical activity components and peer support groups.

Recent U.S. Food and Drug Administration approvals also expanded treatment options, including:

1. Liraglutide (3-mg daily subcutaneous injection):

• Mean placebo-subtracted difference in BMI change was -4.64% (95% CI, -7.14% to -2.14%)
• 43.3% of patients who received the agent achieved a ≥ 5% BMI reduction vs 18.7% in placebo group at 56 weeks
• Common adverse events associated with liraglutide were nausea (42.4% vs 14.3% in placebo group), vomiting (34.4% vs 4.0%), and diarrhea (22.4% vs 14.3%).

2. Semaglutide (2.4-mg weekly subcutaneous injection):

• Mean placebo-subtracted treatment effect on BMI was -16.7% (95% CI, -20.3% to -13.2%)
• 73% of patients who received the agent achieved a ≥ 5% BMI reduction vs 18% in placebo group at 68 weeks.

3. Phentermine/topiramate extended release:

• Mean placebo-subtracted treatment effect was -8.1% BMI (95% CI, -11.92% to -4.31%) for mid-dose (7.5 mg/46 mg)
• -10.44% BMI change (95% CI, -13.89% to -6.99%) for highest dose (15 mg/92 mg)
• Depression rates: 0%, 1.9%, and 4.4% in placebo, mid-, and highest-dose groups, respectively.

Metabolic and bariatric surgery led to a reduction in mean BMI of up to 30% at 3 to 8 years. This intervention was associated with improvements in hypertension, type 2 diabetes, dyslipidemia, and obstructive sleep apnea. The 30-day major complication rate was 8%; the 30-day minor complication rate was 15%. Approximately 1,300 to 1,900 adolescents in the U.S. underwent this intervention annually. The Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) Study reported a mean weight decrease of 28% (95% CI, 25%-30%) for Roux-en-Y gastric bypass and 26% (95% CI, 22%-30%) for vertical sleeve gastrectomy at 3-year follow-up. An 8-year follow-up study (n=58) showed a 29.2% BMI reduction after Roux-en-Y gastric bypass. Another study comparing 5-year outcomes between adolescents and adults who underwent Roux-en-Y gastric bypass showed higher remission rates in adolescents for type 2 diabetes (86% vs 53%) and hypertension (68% vs 41%). However, some postsurgical micronutrient deficiencies were noted, such as iron deficiency in 45% to 71% of patients, vitamin B12 deficiency in 20%, and vitamin D deficiency in 41%.

Etiology and Risk Factors

The review also highlighted the complex etiology of adolescent obesity, including genetic, environmental, lifestyle, and social influences. Twin studies estimated the heritability of obesity being between 40% and 70%. More than 750 genetic loci were identified, collectively accounting for 6% of BMI variation.

Other identified risk factors included:

• Short sleep duration: 21% decreased risk of overweight or obesity per 1 hour/day additional sleep (odds ratio [OR], 0.79; 95% CI, 0.7-0.89)
• Recreational screen time lasting ≥ 2 hours/day: increased risk of overweight or obesity (OR, 1.67; 95% CI, 1.48-1.88)
• Poverty: 2.3 times higher likelihood of obesity at age 15.5 years for children experiencing poverty before age 2
• Food insecurity: higher prevalence ratio of 1.3 (95% CI, 1.2-1.5) for obesity.

Long-Term Prognosis

The study emphasized the importance of early intervention, noting that obesity in adolescence strongly predicted obesity in adulthood: 100% of adolescents with a BMI in the ≥ 99th percentile had class 1 obesity (BMI ≥ 30) in adulthood, while 88% had class 2 obesity (BMI ≥ 35) and approximately 65% had class 3 obesity (BMI ≥ 40).

Long-term health risks were significant; for example, adolescents with a BMI in the ≥ 95th percentile had an increased risk of cardiovascular mortality (hazard ratio [HR], 3.5; 95% CI, 2.9-4.1) over 40 years of follow-up. They also had an increased risk of mortality from type 2 diabetes (HR, 17.2; 95% CI, 11.9-24.8).

Conclusions

This comprehensive review provided a thorough examination of the state of adolescent obesity care in the U.S., highlighting the potential of new treatment modalities while acknowledging the need for further research on long-term outcomes and potential adverse effects. The authors recommended a comprehensive approach to treatment, considering all available options based on individual patient needs and preferences.

Conflict of interest disclosures can be found in the review.