Risk of premature death increases, alongside risk of obesity and overweight
A major study that has been published in The Lancet has shown that being overweight or obese is directly associated with a higher risk of premature death. Many recent studies have suggested that excess weight does not have deleterious effects on chronic disease; however this study has highlighted many methodological limitations in previous research. For example, much research had been confounded by smokers, as they tend to have a lower BMI than non-smokers, but a higher mortality.
In 2013, researchers pooled resources to form the Global BMI Mortality Collaboration, involving over 500 investigators from over 300 institutions. The efforts of this group have recently been focused on resolving the confusion between BMI and mortality. In total, this study analysed data from 10.6 million participants across 45 years. It found that those of a healthy weight (BMI between 22.5 and 25) had the lowest mortality, whilst every 5 units above 25 was associated with a 31% higher risk of premature death. The study also found that those who were underweight also had a higher mortality risk. Overall the study has highlighted that the higher the BMI of an individual, the higher their chance of premature death for a wide range of populations.