Wade KH, et al. - Researchers investigated the causal relation of body mass index (BMI) with cardiovascular health in young adults by using Recall-by-Genotype (RbG) in combination with Mendelian randomization (MR). Participants were healthy individuals from the Avon Longitudinal Study of Parents and Children at age 17 years (N=1420–3108 for different outcomes) and an independent sample from the same cohort (for RbG) study at age 21 years (N=386–418). A likely worse cardiovascular impact of higher BMI was suggested even in youth, specifically higher blood pressure levels and left ventricular mass index, by using complementary MR and RbG causal methodologies together with a range of sensitivity analyses. In the RbG study, increased cardiac output caused by higher BMI appeared to be solely driven by stroke volume, as neither MR nor RbG analyses suggested a causal effect of BMI on heart rate. The authors posited that efforts to reduce BMI should be implemented from a young age, and findings suggested the potential for phenotypic resolution with maintained analytic power using RbG.