The rich tend to be slim and clever, while the poor are overweight and less intelligent, claims a survey.
Such is the pressure to be slender that only 6 per cent of 2,000 women polled average age 31 had never dieted.
The poll found that a woman of 31 had been on an average of 38 diets and had first dieted at 18. Nearly one in three women had dieted before their 14th birthday.
The survey, commissioned by a dieting and healthy eating website, said "fatism" was rife and that statistics bore this out.
Full-time working women earning less than £15,000 a year were four times more likely to be overweight than those earning £35,000 or more, and part-time workers earning less than ?6,000 were twice as likely to be overweight than those on £12,000.
Clerical workers were nine times more likely to be overweight (75 per cent) than those at what the survey called director level (8 per cent).
As for female solidarity, forget it, the survey found. Women were far more likely than men to criticise a woman's weight or shape - and 97 per cent of women, fat or thin, admitted they looked at other women in the street and thought "goodness, she's fat".
In fact, the first thing women said they noticed about another woman was her size or shape - only 20 per cent notice her face first. Yet the first thing a woman notices about a man is his face.
Ally Oliver, of Closerdiets.com, which commissioned the survey, said: "In today's society, slim people are viewed as wealthy and bright and fat people are viewed as poor and dim. It's as simple as that.
"Just look at Victoria Beckham, the richer she becomes the thinner she gets, whereas at the other end of the spectrum Matt Lucas's Vicky Pollard is seen as fat, poor and thick." Statistics support the perception that richer people tend to be slimmer than poorer people. It seems you can never be too rich or too thin.
"Weight prejudice is rife and a whole section of society is discriminated against. But this modern weight fascism doesn't seem to affect men. Men can get away with being overweight or body imperfect, women can't - because other women won't let them."
Almost two thirds of women in the survey thought they had lost the ability to eat normally because of a constant battle to stay slim. Only 1 per cent were happy with their body and 54 per cent said they had felt "body hatred" - two thirds of these being women under 25.
Oliver said: "Women today have a toxic relationship with food - a skinny muffin mid-morning is followed by a latte for lunch and a low-fat ready meal topped up with half a bottle of wine and dairy milk for dinner."
The survey was conducted on websites owned by publishing group Emap. The respondents' average weight was just over 11 stone but most wanted to be just over eight stone.