Could obesity rates be even worse than expected?

The rise of obesity rates is now being called an epidemic, in particular in Anglo-Saxon countries. The fact that such a large portion of the population is now considered obese is quite alarming, considering that this was minimal a generation ago, and that the proportion of obese children is even in the double digits in some countries is mind boggling. Could it be even worse?

Yes, according to David Madden who claims that most obesity statistics are based on self-reports for weight and height, from which the BMI (body-mass index) is calculated. Under current standards, a BMI of 30 is considered obese. He suggests that a threshold of as low as 26 should be used to account for the reporting bias in weight. As this bias seems to increase over time (at least in Ireland), the threshold could move down even further. Obviously, this bias will depend on the environment (local culture, context of survey, for example) and could make correct measurement very uncertain. I guess the best way is to actually measure people. One should look into that.