The link between obesity and cardiovascular mortality may be substantially underestimated, while some of the adverse consequences of being underweight may be overstated.  While numerous studies have investigated the link between body mass index (BMI) and mortality, showing that high BMI is associated with higher rates of death from cardiovascular causes, diabetes, and some cancers, inconsistent evidence suggests that low BMI is associated with increased mortality from other causes, such as respiratory disease and lung cancer. Davey Smith, from the University of Bristol (United Kingdom), and colleagues completed a study of over one million Swedish parent-son pairs, tracking the BMI of the sons as young adults with mortality among their parents. The team’s analysis shows strong associations between high offspring BMI and parental mortality from cardiovascular disease, diabetes, and some cancer; most interestingly, however, the team did not find evidence of an association between low BMI and an increased risk of respiratory disease and lung cancer mortality. Stating that: “Our findings suggest that the apparent adverse consequences of low BMI on respiratory disease and lung cancer mortality may be overstated, whereas the adverse consequences of higher BMI on cardiovascular disease mortality may be substantially underestimated,” the researchers propose that: “These conclusions have important implications for public health practice because they suggest that reducing population levels of overweight and obesity (or preventing their rise) will have a considerable benefit to population health. Suggestions to the contrary are probably misguided.”