The fashion industry is ignoring the changing shapes of women's bodies, a study claims today. Designers and manufacturers still insist on making clothes that fit the traditional hourglass figure, when women's shapes are more likely to be top-heavy, rectangular or pear-shaped.

The research found that although only 8 per cent of women now had the sort of hourglass figure flaunted by curvaceous 1950s film stars such as Sophia Loren, designers and manufacturers continued to make clothes to fit a slim-line version of that figure.

Of the 6,000 women's body shapes analysed, 46 per cent were described as rectangular, with the waist less than nine inches smaller than the hips or bust. Just over 20 per cent of women were bottom-heavy "spoons", or pear shapes, with hips two inches larger than busts or more, while almost 14 per cent were "inverted triangles" - women whose busts were three or more inches bigger than their hips.

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The study, by the North Carolina State University, was based on data from a two-year study of American body types, SizeUSA. It was commissioned by Alva Products, a manufacturer of designers' mannequins determined to force the industry to design clothes for the majority rather than the minority of women.

Janice Wang, the firm's chief executive, said: "The majority of retailers are designing clothes for people with an hourglass figure." She added that industry standards for size measurements were out of date. "That needs to change if the industry wants to serve the markets they currently aren't reaching."

The fashion house Liz Claiborne has taken note. David Baron, a vice-president, said it would introduce "gradual changes" to eventually provide "better-fitting" clothes.

Although the study concentrated on American women, its implications were relevant for British women, Ms Wang said, because eating habits and lifestyle meant the shapes of women in the two societies "mirrored each other".

The British fashion designer Katherine Hamnett agreed that women who did not conform to a svelte size 10 continued to be neglected by fashion.

"The fashion industry ignores the true size of women at its peril," she said. "As to why they do, stupidity is the only reason I can think of. It is the result of adhering unthinkingly to a tradition."

And the idea that larger women are not the ideal to design for is a myth. "I have measured film stars who have 42 inch hips, and are still getting a lot of work. It is not how fat you are, it is whether you are fit that matters. People can be beautiful when they are any shape or size."

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Breast enhancements and other types of cosmetic surgery could influence the findings, Ms Hamnett said. With breast enhancements likely to create the "inverted triangle" body type, the popularity of cosmetic surgery means there are new shapes that are less likely to be affected by diet or exercise.

The findings concur with a similar study of British women, SizeUK, published late last year, which found that the average woman's waistline had expanded by six inches since the 1950s.

Carried out by University College London and the London College of Fashion, the study found that women and men had shot up and out, with today's woman taller, with a bigger bust and hips than her 1950s counterpart.

Hourglass

Exemplified by the actress Sophia Loren, only 8 per cent of women tend to have equal hip and bust measurements with a narrow waist

The spoon

Just over 20 per cent of women, like Jennifer Lopez, have a pear-shaped figure, where the hip measurement is larger than the bust

Rectangular

Forty-six per cent of women fit this shape, where the waist is less than nine inches smaller than the hips or bust. Mel C is a good example

Inverted triangle

Another modern outline, where the bust is bigger than the hips. The swimmer Sharron Davies is one of the 14 per cent who fits this shape