The research functioned this way: some viewers were shown sexist ads and others were shown non-sexist ads.

Those who saw the sexist ads judged their current body size as larger - and, more significantly, had a bigger difference between their actual body size and what they felt to be their ideal body size.

They preferred a thinner body to those who were exposed to the non-sexist ads.

Here we are in 2013. And the women used to advertise sunscreen, sports shoes and sex toys are more stereotypical than ever, even though researchers say it makes us feel worse about ourselves. More dissatisfied. Less realistic.

I can't watch a B-grade movie (a secret obsession of mine) without being exposed to waggling bottoms and wiggling lips. It is, apparently, not possible to buy fast food in our nation without attending the shop counter in a bikini, the bottom half of which you use to pop in the two bucks you received in change.

In Australia, everyone eats their burgers and chicken wings partially clad. This way, we save on laundry. And clothes.

This is not a request for advertising without stereotypes. I'm afraid that many of the people who work in the advertising industry in Australia would have nothing in their folders if we asked for original concepts each and every time. But I am going to ask for this - if you plan to sell me something based on ethics, you need to pitch it right.

New research led by Renata Bongiorno at the University of Queensland, with Paul Bain and Nick Haslam, tells me that if you are trying to sell an ethical product or idea, sex won't do it.

Sex has many magical properties (yes, feel free to try it at home). But selling ethics is not one of them.

Bongiorno conducted two experiments: one with a group of Australian male undergraduates, and the second with a community sample of men and women in the United States - and showed them some advertisements for animal activists PETA (People for the Ethical Treatment of Animals). The groups saw either sexualised or non-sexualised PETA ads: ones where women were fully clothed and ones where the women were either in lingerie or in the buff.

What Bongiorno found confirmed her suspicions.

Sexualised women were dehumanised, were seen as more animal-like. Men and women were less likely to support PETA's cause.

''There's a negative link between dehumanisation and the treatment of others, it reduces concern … if you are using images that are dehumanising, it's likely to backfire.''

Advertisers, says Bongiorno, need to understand the effect these images have on people. And she says that PETA needs to understand this basic psychology before its next round of advertising.

Men, less likely to support animal welfare anyhow, were aroused by the images but that had no positive impact on supporting the PETA cause.

Their responses demonstrated that the young men were put off supporting the cause because the sexualised images dehumanised women.

Claire Fryer, the campaigns co-ordinator for PETA, is unimpressed by the research. She says the study has a major flaw because it ignores the impact that sexualised advertising has.

''Time and time again, protests featuring fully clothed people cramped in cages to demonstrate the suffering that monkeys bound for experimentation endure on long-haul flights, or activists dressed in chicken costumes to protest KFC's lack of animal welfare standards, never grab the headlines, garner attention, or get TV airtime as ones with sex appeal do.''

She cites the example of PETA US vice-president Dan Mathews after two guest speaking engagements at Harvard University. His ''I'd Rather Go Naked Than Wear Fur'' protest gained national media coverage, his non-naked protest gained none.

Fryer also says that they are equal opportunity in their exploitation of the human body - both men and women go naked to draw attention to animal suffering ''but media coverage of women vastly outweighs coverage of men''.

Dr Bongiorno says Fryer is confusing impact on - and coverage in - media with a very real change in perceptions of consumers whose support is being sought. ''Yes, it generates publicity but is it doing it in a useful way, that's the question.''

Jane Caro, advertising consultant and panellist on The Gruen Transfer, agrees with Bongiorno's findings. ''Sex only sells if you are trying to sell sex,'' she says.

Twitter @jennaprice or email jenna_p@bigpond.net.au