A study of 1.46 million white adults found that both overweight and obesity (and possibly underweight) are associated with increased all-cause mortality. The lowest all-cause mortality was generally observed in the BMI range of 20.0 to 24.9. The study used Cox regression to estimate hazard ratios and 95% confidence intervals for the association between BMI and all-cause mortality, adjusting for age, study, physical activity, alcohol consumption, education, and marital status. The results showed a J-shaped relationship between BMI and all-cause mortality, with the highest risk for BMI categories below 20.0 and above 25.0. The hazard ratios for BMI below 20.0 were attenuated with longer-term follow-up. The study also found that the association between BMI and all-cause mortality varied with smoking status and prevalent disease. The findings were consistent with previous studies, suggesting that an optimal BMI range for minimizing all-cause mortality is 20.0 to 24.9. The study's main limitations included reliance on self-reported data and a focus on non-Hispanic white individuals. The results are most relevant to whites in affluent countries.A study of 1.46 million white adults found that both overweight and obesity (and possibly underweight) are associated with increased all-cause mortality. The lowest all-cause mortality was generally observed in the BMI range of 20.0 to 24.9. The study used Cox regression to estimate hazard ratios and 95% confidence intervals for the association between BMI and all-cause mortality, adjusting for age, study, physical activity, alcohol consumption, education, and marital status. The results showed a J-shaped relationship between BMI and all-cause mortality, with the highest risk for BMI categories below 20.0 and above 25.0. The hazard ratios for BMI below 20.0 were attenuated with longer-term follow-up. The study also found that the association between BMI and all-cause mortality varied with smoking status and prevalent disease. The findings were consistent with previous studies, suggesting that an optimal BMI range for minimizing all-cause mortality is 20.0 to 24.9. The study's main limitations included reliance on self-reported data and a focus on non-Hispanic white individuals. The results are most relevant to whites in affluent countries.