Online Exercise Program and Dietary Advice (FITT-online) for Children and Adolescents With Obesity

Inclusion Criteria: 1. Simple obesity: Body mass index (BMI) between +2SD and +3SD of the reference range: based on the "Standard Deviation Curve of BMI for Children 0-18 Years of Age in China", which was developed by the Physical Development Survey of Children in Nine Provinces/Cities in 2005; 2. Not participating in other weight management programs currently or in the 3 months prior to the study; 3. Accepts to participate and signs informed consent. Exclusion Criteria: 1. Currently taking or planning to take medications or interventions that affect body weight during the study period (32 weeks) 2. Obesity caused by other medical conditions. For example, hypothalamic-pituitary disease, hypothyroidism, growth hormone deficiency, Cushing's syndrome, obesity-related syndromes. 3. Comorbidity with other chronic diseases. E.g. psychiatric diseases, respiratory diseases, gastrointestinal diseases, rheumatic diseases, hepatic and renal insufficiency, chronic infectious diseases; 4. Presence of abnormal laboratory values at the time of screening indicating a clinically significant underlying disease or condition that may prevent the subject from participating in the study; or presence of abnormalities in the following laboratory tests: alanine aminotransferase (ALT) greater than 5 times the upper limit of normal, serum creatinine (Scr) greater than 1.5 times the upper limit of normal. 5. Contraindications to physical exercise or exercise-related risks. For example, history of asthma, history of hypoglycemia/diabetes, history of heart disease, history of cardiovascular disease, fracture/surgery/planned surgery within the last 1 year, psychomotor retardation, motor system defects/disabilities, previous history of exercise intolerance;