This retrospective study analyzed the effects of an interdisciplinary intervention on anthropometry and body composition in children with obesity and severe obesity. The children participated in the Childhood Obesity Center at Hospital Varela Santiago between 2021 and 2024. The study hypothesis considered that the multiprofessional approach would result in significant improvements in body and metabolic health in children with obesity and severe obesity. The analysis included 143 children (71 girls) aged 8.1 ± 1.4 years. A total of 8 evaluations per year were conducted (e.g., each child was assessed for up to 8 months in the year they started treatment). Participants had their body mass, height, and body composition (bioimpedance) assessed every 21 days. Outcome measures included body mass index (BMI), BMI standardized for sex and age (BMI-z), obesity severity as BMI relative to the 95th percentile (%BMIp95), body fat percentage (%F), fat-free mass (FFM), and trunk fat. Based on %BMIp95, children were divided into two groups according to obesity severity (obesity – BMI between 100% and 120% of the 95th percentile for age and sex – and severe obesity – BMI > 120% of the 95th percentile for age and sex). Mixed linear models were used to investigate the treatment effect (months 1 to 8) on the assessed parameters. To compare potential differences between children with and without severe obesity, the interaction between treatment and obesity severity was evaluated. Models were adjusted for sex and age. A significant reduction was observed in BMI (b = -0.15; 95% CI = -0.21 – -0.09 kg/m²; p < 0.001), BMI-z (b = -0.02; 95% CI = -0.04 – -0.01; p < 0.001), and %BMIp95 (b = -0.71; -0.99 – -0.43%), regardless of sex and age. After the 8 evaluations, there was a cumulative loss of 1.2 kg/m² in BMI, 0.16 units in BMI-z, and 5.6% in obesity severity. Improvements in body composition were also observed, with an average gain of 500g in fat-free mass, a 3% reduction in body fat percentage, and a 1kg decrease in trunk fat. Analyses indicated an interaction between obesity severity and treatment. Children with severe obesity showed greater reductions in BMI, BMI-z, and %BMIp95, but not in body composition variables. The results reinforce the effectiveness of continuous and tailored interdisciplinary strategies, contributing to the literature on public childhood obesity treatments.