Strengthening the Triponderal Mass Index as a Clinical Tool for the Diagnosis and Monitoring of Childhood Obesity: A Big Data Perspective

Background and Objective: The diagnosis of childhood obesity has historically relied on the Body Mass Index (BMI), which is biologically imprecise during the growth stage due to variations in adiposity rebound and the pubertal growth spurt. This study aims to validate the Tri-ponderal Mass Index (TMI), which accounts for the three-dimensional expansion of the human body, against BMI at a population level. It uses Primary Care Big Data to improve the early detection of metabolic risk. Materials and Methods: An observational, cross-sectional study was conducted using electronic health records from the Basque Country public health network (Osakidetza) for the year 2026. Following a rigorous data cleaning process, a validated cohort of 21,371 patients aged 0 to 18 years was analyzed. TMI and BMI values were grouped by exact decimal age (in 0.5-year intervals) and statistically compared against the 2011 Orbegozo Foundation population reference standards. Results: While BMI displayed the classic biphasic “J-shaped” curve, TMI demonstrated a remarkable biological plateau and robust cross-sectional stability between 6 and 14 years, consistently fluctuating between 13.0 and 14.5 kg/m³. Furthermore, the contemporary cohort exhibited significantly higher body mass (p < 0.001) compared to the historical 2011 Or-begozo standards from 9.5 years onwards. In addition, the baseline stability of TMI facilitated a clearer statistical detection of the subpopulation with extreme adiposity and high metabolic risk. Conclusions: TMI proves to be a biomechanically superior, more stable, and physiologically coherent index than BMI between the ages of 6 and 16. It is posited as the clinical tool of choice in Primary Care to identify the metabolically unhealthy obese phenotype and optimize patient referrals to Pediatric Endocrinology.