More media images of full-figured models could help break the unhealthy obsession many women have with being thin, new research suggests.

Psychologists found that photos of catalogue models exerted a powerful influence on attitudes to body size.

After being shown pictures of plus-size models, women who started out with a strong bias in favour of slimness became significantly less keen on thin bodies.

But after seeing similar photos of slender models, their preference for thinness increased.

Preferences also shifted away from thinness when "aspirational" images of well dressed, attractive and glamorous larger models were paired with plain pictures of underweight women.

Study leader Dr Lynda Boothroyd, from the University of Durham, said: "This really gives us some food for thought about the power of exposure to super-slim bodies.

"There is evidence that being constantly surrounded through the media by celebrities and models who are very thin contributes to girls and women having an unhealthy attitude to their bodies.

"Although we don't yet know whether brief exposure to pictures of larger women will change women's attitudes in the long-term, our findings certainly indicate that showing more 'normal' models could potentially reduce women's obsession for thinness."

The study involved more than 100 women who were told they were taking part in research on body perception.

In two trials, the women were shown images of thin and plus-size models from fashion catalogues and beauty contests, and ordinary women in plain grey leotards who were either under or overweight.

The plus-size models had a minimum clothes size of 16.

Participants recorded their body size preferences at different stages during the research using a scoring system.

The results were reported in the online journal Public Library of Science ONE.

They supported the idea that in Western culture, thinness was associated with good health and high status, researchers said.

An opposite view exists in some developing countries, where having a full figure is seen as an indicator of health, wealth and femininity.

"Thinner bodies are definitely in vogue and within Western media, thinness is overwhelmingly idolised and being overweight is often stigmatised," Dr Boothroyd said.

"Although the media doesn't directly cause eating disorders, research suggests it is a very powerful factor in creating body dissatisfaction."

Even so-called "cautionary" images warning of the perils of anorexia may increase preferences for thinner bodies, Dr Boothroyd said.

She cited the example of the late anorexic French model Isabelle Caro, who gained worldwide publicity for posing nude for a campaign to increase awareness of the illness.

"These campaigns may not have the desired effect which is a sobering thought," she added.

Susan Ringwood, chief executive of the eating disorders charity Beat, said: "This study points towards an important aspect of our modern lives.

"We see an average of 2,000 images a day in advertising alone, and most of these include bodies that are more slender than average.

"Increasing the diversity of body shapes and sizes portrayed in the media could rebalance our views about our own bodies in an emotionally healthy way."

One of the charity's volunteers, Rachel Cowey, 25, from South Shields, who developed anorexia aged 16, said: "There is an immense pressure to be seen to have it all and be perfect at everything.

"Within the media, being thin and attractive is linked to being successful.

"The doctors told me it was impossible to survive at the weight I was, yet the media constantly showed skinny celebrities who were apparently absolutely fine.

"That was hugely unhelpful for my mindset and recovery."