A BMJ study (criticized here) found that, among people with a BMI of 26, 60% said that they were overweight in 1999, but only 40% said so in 2007. The study concluded that millions of people were too stupid to know that they were fat. Official charts say that anyone with a BMI over 25 is overweight.
A 2005 JAMA study found that folks with a BMI of 27 live the longest. Maybe 20% of the population has wised up to current research, and it is the official BMI tables that are out of date.