Most of the people who have crossed the line of obesity fail to realise that they are above normal weight, according to a new survey.
The poll, carried out by YouGov for Slimming World, found that almost a quarter of the 2,000 people questioned had measurements, which would place them squarely in the obese camp.
However, there were only 7 percent of those asked, who classified themselves as so.
Over half of those deemed morbidly obese believed that they ate a healthy diet, while more than a third of the overweight said they had never tried to shed the pounds.
The findings clearly suggest that we are suffering from a phenomenon that indicates that as those around us get fatter, our perceptions of our own size change accordingly.
While many have found solace in the suggestion that Marilyn Monroe was apparently a size 16, they don't realise that dress sizes have changed dramatically down the decades as our bodies have grown, and those who can squeeze into a size 8 today would not have been able to do so in 1940.
Thus, researchers have said that the discrepancy has widened with worryingly few people recognising their weight is potentially harmful to them.
While our life expectancies have increased at the same time as our weight, the consensus now is that cases of diseases such as diabetes and even cancer could be reduced if everybody strove to be within the "normal" Body Mass Index (BMI) range.
However, people's perceptions of normal have changed.
"In my view there is a very clear tendency for individuals with obesity to feel that they do not stand out from the crowd," said Jonathan Pinkney, a consultant in endocrinology and diabetes from the Association for the Study of Obesity (ASO).
Thus, experts have suggested that people should calculate their BMI.
"This is because the median BMI has increased so much. For example, if some 4% of women now have a BMI of more than 40, then arguably you need this sort of BMI to begin to look obviously obese when you walk down the street.
"That may be one reason why self-reported obesity underestimates its true prevalence," added Pinkney.
The focus on the extreme in television documentaries about the very large but also in the pictures that are chosen to illustrate articles about obesity have also been held up as another potential culprit.
"If you see people with BMI of over 50, say, and you have a BMI of 40 then you may well think you aren't too bad," said Dr Krystyna Matyka, of the University of Warwick Medical School.
Recently, Australian research found that half of parents thought their child of average weight when in fact they were overweight-a trend that could further augment the problem of obesity.