[Overweight, obesity and life expectancy: do people with a high BMI live longer?]

- The relationship between BMI and relative mortality risk is J- or U-shaped; both a low and a high BMI are related to increased risk of mortality.- When analyses are restricted to healthy individuals who are non-smokers and are followed up for a long time, the relative mortality risk is already increased at a BMI of 25 kg/m² and increases further with increasing BMI.- There are people with obesity who do not have significant cardiovascular risk factors, but even so they are at increased risk of cardiovascular disease compared to people who are not overweight and lack risk factors.- People with severe illnesses often experience weight loss and - at the same time - are at increased risk of premature death, and therefore it appears that overweightness is associated with a favourable prognosis.- The observation that overweight and obese people are not linked to increased mortality can largely be explained by methodological sources of bias.