Clinical Obesity Rising Among U.S. Adolescents

Clinical obesity increased among U.S. adolescents over the past two decades, underscoring the urgent need for targeted prevention and intervention.

According to a serial cross-sectional analysis of National Health and Nutrition Examination Survey (NHANES) data published in a JAMA Pediatrics research letter, excess adiposity — defined as a body mass index (BMI)-for-age at or above the 95th percentile with a waist-to-height ratio of at least 0.50 — rose from 14.2% in 1999-2000 to 18.2% in 2021-2023 among adolescents ages 12 to 19 years.

Concurrently, rates of clinical obesity, or excess adiposity accompanied by organ dysfunction, nearly doubled from 5.3% to 9.2%. Rates of preclinical obesity, defined as excess adiposity without organ dysfunction, remained stable at around 9%.

“Adolescent obesity has been a concern for many years, and we are increasingly seeing obesity-related health problems appear at younger ages,” study author Ligang Liu, PharmD, MPH, of Western University of Health Sciences in Pomona, California, told MedPage Today.

“It is important not to view adolescent obesity only as an individual lifestyle issue. The environments in which young people eat, sleep, study, use technology, and spend time all influence risk,” he added.

Defining Clinical Versus Preclinical Obesity

The findings indicate that a growing proportion of adolescents with excess adiposity already exhibit organ system damage, affecting cardiovascular, metabolic, hepatic, and respiratory systems.

Organ involvement varied widely among adolescents with clinical obesity. The most common isolated manifestations were:

• Respiratory dysfunction: 26.5%
• Metabolic cluster abnormalities: 23.6%
• Cardiovascular dysfunction: 18%
• Hepatic impairment: 7.4%

“Clinical obesity is more concerning in terms of current health because it means that excess adiposity is already accompanied by evidence of organ dysfunction or functional impairment,” said Liu.

He emphasized that while preclinical obesity lacks immediate organ damage, it still carries substantial future risk, making early prevention critical.

Looking Beyond BMI

Because organ dysfunction varies significantly among adolescents, experts stress that clinicians cannot rely on BMI alone.

“BMI remains useful for screening, but it does not tell us whether excess adiposity is already affecting an adolescent’s health,” Liu noted. “Two adolescents with a similar BMI can have very different health profiles and require different levels of care.”

Eugene Lucas, DNP, of Wilkes University in Wilkes-Barre, Pennsylvania, highlighted other key clinical markers for clinicians to evaluate in pediatric patients:

• Growth trajectory: rapid percentile acceleration or adiposity rebound before age 5 years
• Dermatological signs: acanthosis nigricans indicating insulin resistance
• Respiratory and musculoskeletal symptoms: snoring or daytime sleepiness indicating sleep apnea; hip pain or limping suggesting slipped capital femoral epiphysis
• Cardiovascular and renal signs: hypertension, polydipsia, and polyuria
• Lab markers: elevated fasting glucose, HbA1c, triglycerides, liver enzymes, and inflammatory markers (e.g., C-reactive protein), and low high-density lipoprotein (HDL) cholesterol

Socioeconomic Disparities, Environmental Stress

The NHANES data also revealed significant health equity gaps. Rates for clinical obesity rose from 4.8% to 11.7% among adolescents from low-income households, whereas higher-income households saw no significant increase (P for interaction=0.02).

Liu pointed to systemic barriers, including limited access to nutritious food, safe recreational spaces, and specialty care, as major drivers.

“Young people are growing up in environments that can make healthy eating, regular physical activity, and adequate sleep more difficult, while social and economic stress may add to the problem,” he noted. “From a public health perspective, prevention requires attention to the food environment, opportunities for physical activity, sleep, mental health, and the social conditions that make healthy choices easier or harder for families.”

Lucas said that mental health and chronic stress play a direct biological role in weight trajectories. Personal and family stress trigger elevations in cortisol, which dysregulate hunger hormones and metabolic control.

Medical Therapies and Interventions

When lifestyle modifications prove insufficient, medical intervention may be appropriate. GLP-1 receptor agonists like liraglutide (Saxenda) and semaglutide (Wegovy) are approved by the FDA for weight management in adolescents ages 12 years and older.

Guidelines allow for consideration of use in children as young as 8 years, and liraglutide, semaglutide, and tirzepatide (Zepbound) either have been studied or are being studied in kids ages 6 to 11.

Lucas noted that off-label use in children ages 6 to 11 may be considered in severe cases involving a BMI over 40, type 2 diabetes, fatty liver disease, or severe hypertension. However, risks include gastrointestinal side effects, loss of muscle mass, gallstones, pancreatitis, and potential cardiac strain.

Other weight-loss agents, like phentermine and amphetamines, carry side effects such as decreased appetite, headaches, trouble sleeping, gastric upset, nervousness and increased anxiety, and moodiness and irritability, he added.

Bariatric surgery remains an option for severe cases for which benefits outweigh risks, although it is rarely covered for people under age 18, said Lucas. The landmark Teen-LABS study “found greater benefits for teens in outcomes than adults as far as lasting benefit, but risks include infection, bleeding, and improper wound closure,” he pointed out.

“The approach to weight management in children requires a comprehensive evaluation, including mental health, dietary habits, laboratory studies, genetic and cultural factors, family history, and food security,” Lucas advised. “A multidisciplinary team approach is essential.”