People’s Perception of Their Own Weight

The National Health and Nutrition Examination Survey (NHANES) is conducted by the National Center for Health Statistics and the Center for Disease Control. It is really a group of long-term studies, and each one surveys a large, representative sample of United States citizens aged 2 months and up. The survey includes a face-to-face interview, a physical exam including calculation of their Body Mass Index, and several laboratory tests.

When we talk about the rise in overweight and obesity in America, it is most often this study that is cited. Data from a stage of this study performed between 1988 and 1994 is compared to data collected between 1999 and 2000 to show that the percentage of Americans who are clinically overweight or obese have risen from 32% overweight and 22.5% obese to 34% overweight and 30.5% obese. But wait - there's more: the survey data collected in 2003 and 2004 show 34% of Americans over 20 years of age are overweight, while 32% are obese.

Clearly, this is bad.

A study recently published in the International Journal of Behavioral Nutrition and Physical Activity (2008; 5:9 5868-5-9) makes use of other information collected in the NHANES series of surveys: people's perception of themselves as overweight or obese. During the face-to-face interview, the survey subjects were asked if they considered their weight to be underweight, overweight, or just right. (They were also told that their weight would be measured.) The researchers looked at the weight perception responses for all of the people age 20 and over whose height and weight measurements indicated that they fell into the Body Mass Index range of 25.0-29.9 (clinically overweight).

They found that for the earlier stage of NHANES (1988-1994), 68% of people who were overweight correctly identified themselves as overweight. The later stage, 1999-2004, however, had only 62% of people who were overweight correctly identifying themselves as overweight. Six percent fewer people were perceiving their weight status correctly. What's scary, though, is that those men and women between 20 and 34 were much less likely to see themselves as overweight: 13% fewer people between the earlier stage of the study and the later stage.

What this means for you

It's pretty clear that people's perceptions of their own weight are skewed - perhaps because so many more people are overweight now than in the past. But the perception of overweight as "normal" (in the sense of "common") doesn't mean that being overweight is any healthier than it has ever been. Maintaining your Body Mass Index in the normal range (20 - 24.9) is still the single most effective way for you to protect your health. What's your Body Mass Index - and how does it look to you?

First posted: April 23, 2008