It is well known that women often view themselves as "too fat" while men typically underestimate their weight. But how far has people's perception of their weight changed with the growing obesity epidemic?
Researchers from the Health Behaviour Research Centre at University College London, compared data taken from two household surveys carried out in 1999 and 2007. In each survey participants were asked to give their height and weight (from which their BMI and clinical weight category could be determined) and also categorise themselves as either: "very underweight", "underweight", "about right", "overweight" or "very overweight". The 2007 survey also included "obese" as a category.
Professor Jane Wardle and colleagues found the proportion of respondents whose weight placed them in the clinically obese category had nearly doubled in eight years from 11% in 1999 to 19% in 2007. Yet, those whose weight put them in the overweight category were less likely to think that they were overweight in 2007 than in 1999.
In 1999, 43% of the population had a BMI that put them in the overweight or obese range, of whom 81% correctly identified themselves as overweight. But in 2007, 53% of the population had a BMI in the overweight or obese range, but only 75% of these correctly classed themselves as overweight.
The researchers suggest that the growing division between actual and perceived weight may be due to overweight becoming more widespread in the population and the appearance of mild overweight being increasingly accepted as "normal". These changes may have increased the level at which people perceive themselves to be overweight.
According to the authors, these perceptions are reinforced by media images of people who are morbidly obese, which add to the misconception that extremely high weights are required to meet the medical criteria for overweight. This can also increase the stigma attached to the labels "overweight" and "obese".
The authors warn that despite media and health campaigns aimed at raising awareness of healthy weight, increasing numbers of overweight people are failing to recognise that their weight is a cause for concern, or that messages about healthy eating and exercise are aimed at them.
Overweight people, who underestimate their body weight, may be ignoring important messages about modifying their lifestyles, claims Professor Sara Bleich from John Hopkins Bloomberg School of Health in an accompanying editorial.
According to Bleich, the key to correcting misconceptions about weight is to treat obesity as a multilevel problem – focusing on broader society as well as the individual. Educating the entire population on the importance of a healthy lifestyle, rather than focusing on overweight individuals, may also reduce weight-related stigma.