This service is based on an integrated smart platform providing content and services that are planned and established through cooperation with service providers such as hospitals and public health centers, obese children/teenagers who constitute the service's user base, and IT development and policy institutions and companies with a focus on child-teen obesity management and treatment (Figure 1).

Patients (obese children/teenagers) enter information about their activity level, exercise and meals through the health tracker and are managed by experts (medical staff members) based on the entered information. Patients are also provided with various types of information related to nutrition and exercise and communicate with responsible experts to correct improper aspects of their lifestyles that have been diagnosed through medical interviews and consultations. The parents of patients may check the information regarding their children's exercise, meals, treatment, management and other aspects of their progress through the mobile service. Experts monitor the patients in real-time based on the health information entered through the monitoring app service exclusively for that purpose and continuously communicate, providing information and interventions tailored to each patient.

Additionally, a service termed the 5-Minute Appetite Endurance Food Craving Service was planned and developed to help patients to suppress excessive impulse eating due to sudden appetite increases (Figure 2).

The target structure and a process map of this child-teen Obesity treatment service platform are summarized in Figure 3.

A child/teenager joins this service for obesity management and treatment by visiting a pediatrician for physical and body composition measurements. The expert registers the patient by entering the measurement information. The patient takes a physical fitness test consisting of various steps along with medical inquiries to detect poor health behavior and starts to wear an activity tracker. The expert provides consultations on nutrition and exercise and sets short- and long-term goals based on the test results. Later, the patient continuously uses the service by entering information about their emotions, meals and exercise. The expert then monitors this information and manages the patient's goal achievement status while the patient periodically visits the clinic for further physical measurements to check how far they have progressed toward their goal. All of the information is shared between the clinic, the patient and the parents, serving to increase the effects of the treatment.

The treatment and management program of this service is based on the principles of child-teen obesity management included in the guidelines of the American Academy of Pediatrics (AAP) for child/obesity treatment and management and the obesity treatment guidelines of the Korean Society for the Study of Obesity [3]. Interventions are classified from Stage 1 to Stage 4, with a total of four stages. Stage 4 is the most intense level of intervention (Figure 4).

Aspartate aminotransferase (AST), alanine aminotransferase (ALT), serum cholesterol, neutral fat, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, electrocardiogram, fasting blood glucose, hemoglobin A1c, urine and blood pressure are tested for any obese children/teenagers having a body mass index exceeding the 95th percentile for their gender and age. Lung function is tested for obese children/teenagers who are suspected of experiencing difficulty breathing during sleep. Tests for medical risks (past disease and treatment record, growth development, parents' obesity, family history, lab tests), behavioral risks (sedentary time, meal amounts, physical activity level) and attitude (interest and motivation levels for the family and the child) are conducted. The intensity and stage of intervention are set based on the results and include a mid-to-high intensity weight-control program which includes behavioral control, exercise and nutrition management aspects lasting at least one year.

The same factors are assessed for the overweight group with a body mass in the 85th–94th percentile and, if there is determined to be any health risk, a mid-to-high-intensity weight-control program including behavioral control, exercise and nutrition management is established and carried out for at least 1 year.

Management of specific groups of children/teenagers is performed by classifying the children/teenagers into four groups according to their obesity level and risk factors, as shown in Table 1.

All children/teenagers are managed from Stage 1 regardless of their group. Goal achievements are evaluated every 3 months for G1 and G2 and every month for G3. If the goal has been achieved, the stage is maintained. If the goal has not been achieved, the stage is upgraded to the next one. Stage 3 is maintained if the child has failed to achieve their goal. However, if the triglyceride glucose (TyG) index value is higher than the set point or if it is determined that an expert is required, the initial stage can be changed. Table 2 shows the intervention strategies used at each stage.