Australasian Science: Australia's authority on science since 1938

I Want Your Body

By Tim Olds

One-quarter of women would give up 3 years of their lives to be their ideal weight, but what do people believe is the ideal body?

In my undergraduate days I worked in a gym, a kind of apprenticeship that all exercise science students must go through in the hope that the oppressive triviality of the job will make them aspire to higher things, like injecting footballers with dubious ergogenic substances. One meets all types in the gym, including people like Zara.

Zara came to me for an exercise program and took me on a tour of the gym, telling me exactly what sort of body she wanted. It was no ordinary body, rather a composite of what she considered the best of the best. She wanted Adam’s abs, Bianca’s boobs, Coralie’s calves … I decided then that my future did not lie in the fitness industry.

Zara is not alone in wanting to build an ideal body. A Psychology Today survey found that 25% of women and 17% of men would give up 3 years of their lives just to be their ideal weight.

So what makes an ideal body? One approach is to look at “hyperideal” bodies – supermodels, shop mannequins, porn stars. One can even, as my colleague Kevin Norton and I did, measure that most iconic of all bodies, Barbie, which we did using Vernier calipers and dental floss.

In women, thinness is critical. Garner and colleagues looked at Playboy centrefolds — yes, it’s tough work, but somebody has to do it – showing that their weight fell from 90% of the average for young American women in 1960 to just 80% in 1980. The body mass index of the average Australian woman is about 26. In exercise science students it is 22, in catalogue models 20, in porn stars 18, in supermodels 17.5, in shop mannequins 17 and in Barbie 14.5, a level achieved by about one in every 100,000 Australian women, usually as a result of some life-limiting illness.

Shapeliness is the other factor. The waist-to-hip girth ratio is a good measure of how attractive men (and women) find women’s bodies. Lower is better. Men lust after women with ratios about 0.6–0.7. The average young woman scores about 0.75, exercise science students 0.72, catalogue models 0.70, porn stars and supermodels 0.69, and Barbie 0.56.

The modern reader will not, I’m sure, be scandalised to learn that bust size also matters. One composite measure of shapeliness in women is the “hourglass index”, which is chest–waist ratio divided by waist–hip ratio. In this case, higher is better. For athletic young women the hourglass index is 1.8. It is 1.9 for catalogue models, 2.0 for shop mannequins, 2.1 for porn stars, 2.2 for supermodels, and a quite dizzying 3.5 for Barbie.

Barbie’s most extreme characteristic, however, is her feet. Barbie’s foot length is 17 standard deviations below the mean, an occurrence about as probable as Julia Gillard becoming Kevin Rudd’s campaign manager after the next election.

Zara might disagree but the body is not everything – there’s still work to be done on the face. A study by Perrett (Nature, 368, 239–42) asked people to rate the attractiveness of female faces, and measured the differences between those considered the most beautiful and those considered more plain. In both the UK and Japan the key differences were the same: a more rounded jaw, more arched eyebrows, larger eyes, and smaller distances from the tip of the chin to the lower lip, and from the upper lip to the bottom of the nose were all considered more beautiful.

Facial symmetry is also important. Men, women and infants prefer more symmetrical faces, and symmetrical couples report more orgasms. Symmetry is seen as a marker of the ability of the body to resist the injuries and insults of everyday life, and hence an “honest advertisement” of good genetic material. Unfortunately, in a study of facial symmetry in our lab, I turned out to have the least symmetrical face of all of us. I must talk to my wife about this.

So why do we find thinness and shapeliness attractive? Each side in the culture wars has drawn up its battlelines in this debate. Cultural theorists argue that body ideals are socially constructed, and cite as evidence historical ups and downs in preferences, from the corpulent nymphs of Rubens to the locust-like stick figure of Twiggy.

We are conditioned, they say, by the models we have around us, and boys are not immune. The average bicep size of GI Joe “action figures” (not dolls!) more than doubled between 1965 and 1995.

Sociobiologists, on the other hand, argue that thinness, shapeliness and symmetry are markers of youth and fecundity – the readiness of women to bear children – and that we are programmed to find these traits attractive.

And Zara? She ended up studying exercise science.

Professor Tim Olds leads the Health and Use of Time Group at the Sansom Institute for Health Research, University of South Australia.