Wade KH, et al. - Through a record-linked, intergenerational prospective study from the general population of Sweden, researchers obtained estimates of the causal relation of BMI with all-cause and cause-specific mortality. Two-sample instrumental variable (IV) analysis with data from 996,898 fathers (282,407 deaths) and 1,013,083 mothers (153,043 deaths) and their sons followed up from January 1, 1961, until December 31, 2004, were utilized. Consistent with former large-scale meta-analyses and reviews, conclusions supported the causal role of higher BMI in increasing the risk of several common causes of death, including cancers with increasing global incidence. Positive impacts of BMI on mortality from respiratory disease, prostate cancer, and lung cancer, which has been eccentrically reported in the literature, implying that the causal role of higher BMI in mortality from these diseases may be undervalued, was discovered. Moreover, various patterns of bias in the current observational and IV analyses was expected and hence, the connections between the findings from both methods raise confidence in the results. These conclusions support efforts to learn the mechanisms underpinning these impacts to report targeted interventions and develop population-based approaches to decrease growing obesity levels for disease prevention.