According to this article in The Guardian, there are a lot of people who just aren’t aware of their body composition.
The article references a non-scientific study in which approximately 300,000 people took an online poll asking them to estimate their BMI category– underweight, normal, overweight, obese– then enter their height and weight.
Specifically, the poll discovered that there is a significant difference in perception between men and women. Men tend to be twice as likely as women to underestimate their weight, where women tend to be a little more likely to overestimate. Given cultural norms about weight, this seems to make sense.
The poll also discovered another interesting trend, “healthy” people tend to be more correct in guessing their BMI category, and when they were wrong, they tended to overestimate their weight. In addition, the higher their BMI, the more likely they were to be wrong.
So, while I understand that BMI is a terrible way to measure health and fitness, the findings of this poll are interesting because they suggest, contrary to the documentary, Fathead, that people don’t really know that they are fat.