Childhood Obesity Myth Debunked: Control Weight Gain, Not Crash Diet

March 4 is World Obesity Day, designated by the World Health Organization (WHO). There was a time when childhood obesity was dismissed with the folk belief that "baby fat turns into height." However, since WHO classified obesity as a "21st-century epidemic," the recognition that obesity is a disease requiring management and treatment has taken root.

According to the "2025 Obesity Fact Sheet" published by the Korean Society for the Study of Obesity, the obesity prevalence rate among Korean children and adolescents had been steadily increasing before showing a declining trend after 2021. This resulted from various policy efforts and changes in social awareness. The rate surged to 19.3% in 2021 at the peak of the COVID-19 pandemic, then dropped to 13.8% in 2023, returning to levels similar to 2019, just before the pandemic.

Childhood obesity is not simply a matter of body shape. It causes metabolic abnormalities including fatty liver, dyslipidemia, and blood sugar irregularities. These conditions persist into adulthood, increasing the risk of chronic diseases. Obesity can also lead to gastrointestinal disorders such as indigestion, musculoskeletal problems including knee and hip pain, and respiratory issues such as snoring and sleep apnea. Furthermore, it may be accompanied by psychological and social problems including depression, anxiety, low self-esteem, and difficulties in academic performance and peer relationships. It is a complex health issue affecting the entire growth period.

Childhood obesity is not diagnosed by body mass index (BMI) alone—calculated by dividing weight in kilograms by height in meters squared. Based on pediatric growth charts, a BMI at or above the 95th percentile for age and sex indicates obesity, while at or above the 85th percentile indicates overweight. The condition occurs when caloric intake exceeds expenditure, leading to body fat accumulation. Environmental changes are cited as the underlying cause. During a period when children should be eating well and staying active, multiple factors work together: academic-focused routines from school to private academies, late returns home and irregular meals, frequent dining out and increased processed food consumption, reduced physical activity due to expanded smartphone use, and sleep deprivation. The fundamental cause is the entrenched structure of decreasing activity and increasing sedentary behavior among children.

How should we approach the prevention and treatment of childhood obesity? Setting realistic goals is paramount. Plans must be sustainable while maintaining academics and daily life. The goal should not be creating a thin physique, but controlling excessive weight gain without hindering growth. While this may vary depending on the degree of obesity, during the growth period, simply moderating the pace of weight gain while height increases can constitute meaningful treatment. Diet control and exercise are essential, though this may seem obvious. Reducing dining out, processed foods, and late-night eating while having balanced meals at regular times is important. Adjusting approaches to be feasible considering the child's lifestyle patterns can enhance treatment effectiveness. Rather than sudden high-intensity exercise, it is advisable to consistently engage in activities appropriate for the child's age and body type. The heavier the weight, the greater the strain on joints. Therefore, combining strength training and aerobic exercise is preferable to weight-bearing exercises that stress the joints.

Drug treatment options have also expanded compared to the past. Previously, there were many concerns about prescribing oral obesity medications to children and adolescents due to limited efficacy and side effect risks. Recently, glucagon-like peptide-1 (GLP-1) injectable obesity treatments have been approved for adolescents aged 12 and older. Future obesity treatment options for children and adolescents, including oral medications, are expected to become more diverse. However, drug treatment should be carefully considered only when basic lifestyle modifications such as diet control and exercise prove insufficient and when comorbidities exist or health risks are significant. Establishing lifestyle habits that enable continued weight management after discontinuing medication is most important. Unlike adults, surgical treatment is rarely considered for growing children and adolescents.

Childhood obesity is a disease that can no longer be overlooked. It is difficult to resolve through a child's efforts alone. Meaningful prevention and treatment become possible only when families, schools, and communities work together to create healthy eating habits and living environments. We must remember that health during the growth period is the starting point for lifelong health.

*Lee Dae-yong, Professor of Pediatrics, Chung-Ang University Hospital*