Since stating my intention to join the #BackTo21 campaign to get my BMI back to what it was when I was 21 years of age, I have had several emails and direct messages on social media questioning the wisdom of my intention. Photo by NeONBRAND on Unsplash It is clear that despite BMI being a relatively poor metric of health there is overwhelming evidence that at a population level it predicts poor health outcomes. Importantly there is new data that indicates the target BMI for the prevention of type 2 diabetes and the metabolic syndrome depends on your ethnicity. For people of South Asian origin, there is a call to reset the BMI cutoff to 23.9, which for most people is within the normal range. At the same time, there is a call to classify obesity as an important social determinant of health. Arnaud Chiolero argues below for using BMI as a socioeconomic indicator. Do you agree? Isn’t it quite amazing that in a previous era corpulence was a sign of affluence, whereas in th...