Ashley-Martin J, et al. - In a population-based sample of Canadian children and youth, researchers used data from the Canadian Health Measures Survey to model the development of the tri-ponderal mass index (TMI, kg/m³) between 6 and 19 years of age during childhood and adolescence and to compare the usefulness of the TMI with the body mass index (BMI, kg/m²) to predict cardiometabolic risk. The results obtained from the cross-sectional study indicate that the use of a single sex-specific TMI cut-off for overweight or obesity is hindered by the increase in the measurement variability with age. For both BMI z-score and TMI, prediction accuracy was good for homeostasis model insulin resistance assessment and having ≥3 abnormal tests, fair for C-reactive protein and poor for the remaining results. Weight-for-height indices are likely to have only limited ability to predict cardiometabolic marker levels, and it is unlikely that a change in the scaling power of height improves predictive precision.