By Clare Murphy
BBC News health reporter
Apparently we do not know what's normal anymore
A survey suggests the vast majority of those who are obese do not realise they are so. How is this possible amid what some see as saturation coverage of the nation's burgeoning bellies?
The poll, carried out by YouGov for Slimming World, found just over a quarter of 2,000 people questioned had measurements which would place them squarely in the obese camp.
But only 7% of those asked classified themselves as so.
Over half of those deemed morbidly obese believed they ate a healthy diet, while more than a third of the overweight said they had never tried to shed the pounds.
The findings appear to be fresh evidence of a phenomenon that health professionals have long suspected: as those around us get fatter, our perceptions of our own size change accordingly.
Meanwhile pictures of children too fat to toddle or the adults so large they need to be hoisted from his house have transformed obesity into a freak show rather than a shared problem.
You're bigger than me
Many have found solace in the suggestion that Marilyn Monroe was apparently a size 16: sadly 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.
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.
But our 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," says Jonathan Pinkney, a consultant in endocrinology and diabetes from the Association for the Study of Obesity (ASO).
BODY MASS INDEX
Calculated by dividing weight in kilograms by height in metres squared
Normal: 18.5 - 24.9
Overweight: 25 - 29.9
Obese: Above 30
"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."
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," says Dr Krystyna Matyka of the University of Warwick Medical School.
Not my baby
Studies have also started to document a particular problem among parents in identifying weight issues among their children: Australian research recently found half of parents thought their child of average weight when in fact they were overweight.
But professionals also note the picture is a complicated one. While large may be becoming the norm, the fat - and particularly children - are often seen as a legitimate target for abuse.
"All the discussion around overweight children is so negative that it is not surprising parents find it difficult to acknowledge there is a problem. It's a defence mechanism," says Dr Susan Jebb of the Human Nutrition Research Laboratory of the Medical Research Council.
"We need to get to a point where we can talk about this in a measured way.
"Everybody knows obesity is a problem for the nation, but they don't accept it's a problem for them - as this latest survey shows. We need to give people the confidence to recognise that it is problem, and that it's one they can do something about."