LAUSR

We read with great interest the article by Buscot et al. on child-toadult body mass index (BMI) trajectories and cardiometabolic risk factors in the Young Finns Study. This study followed participants from 6–18 years to 34–49 years of age and is one of few studies with prospective measures of BMI spanning more than 30 years. Latent class growth mixture modelling (LCGMM) identified six distinct BMI trajectories. Five of these trajectories were consistent with other LCGMM studies of BMI from childhood or adolescence to adulthood that have identified 3–5 trajectories broadly characterized as stable normal, stable overweight, increasing overweight, and increasing obesity. In the Young Finns Study, a unique ‘resolving’ trajectory was also identified and characterized by overweight in early life reversing to normal weight range as adults. This ‘resolving’ trajectory was associated with a substantial increase in carotid intima-media thickness suggesting that overweight in childhood may be a sensitive period of exposure. However, only 43 (1.6%) study participants were in the ‘resolving’ trajectory. Understanding the characteristics of participants in this unique ‘resolving’ group may be important in elucidating disease aetiology. Treatment for paediatric overweight and obesity has low success, and behavioural or surgical interventions, may also impact adult cardiometabolic risk factors. Studies with larger sample sizes and more frequent measures of both exposure and outcome are needed to confirm these findings. Further, the period before age 6 years when growth patterns and health behaviours are first established needs to be examined. Lastly, while this study provides important insight on possible mechanism and understanding of the past 30 years, the findings may not be generalizable to current and future cohorts. There were no trajectories that started with obesity and international data suggest there are now 124 million children age 5–19 years living with obesity. Buscot et al. have provided important insights into the role of early life BMI and the possibility of childhood as a sensitive period for cardiometabolic risk supporting the need for primary prevention in addition to treatment for paediatric overweight and obesity.