Visitors to the Defining Beauty exhibition at the British Museum – of sculpture from and inspired by ancient Greece – will be greeted by an ostensibly alluring sight: the naked, crouching figure of Aphrodite beckons us into the room.

Only when we walk around her do we see that her hand may not be beckoning, so much as pulled back to give us a smack in the kisser for looking at her without invitation. For students of body image, she looks a lot more human than many contemporary representations of womanhood: not only does her belly crease as she bends forward, but her feet, frankly, are massive.

This Aphrodite will not fall over on a windy day. For those of us who have spent years with flipper-feet, it’s deeply reassuring.

This Aphrodite will not fall over on a windy day

Nonetheless, the Greeks remind us that impossible ideals of female beauty are at least two and a half thousand years old. A celebrated painter in the fifth century BC, Zeuxis, was given the task of painting Helen of Troy in a depiction of the Judgment of Paris. He couldn’t find a single model to copy; instead, he copied specific features from five girls to achieve the divine figure. No one woman was good enough. It’s hard to avoid the conclusion that human women have fallen short of idealised women since their earliest portrayals.

On the plus side, at least no one asked them to jam themselves into a body-mangling corset or survive on a liquid diet: Aphrodite is slender, but if you tried to withhold her dinner it’s hard not to think she might kick you with one of her mighty feet.

But if the female ideal has changed, the male ideals of beauty from ancient Greece couldn’t look more contemporary. From the hips up, they could come from the cover of Men’s Health magazine: the super-defined abs and rippling pecs are emulated by men all over the world. In terms of male body image, the Greeks are definitely back in fashion.

They aren’t intended to be erotic (hence the small genitals, which are de-emphasised deliberately, to keep the viewer’s mind on higher things). They are beautiful rather than sexy, gazing at the ground, impervious to any lustful stares.

And yet the bronze statue that stands opposite Aphrodite – lost in thought as he scrapes his skin clean of oil and dust (an early sunblock, which came in handy if you exercised in the nude in a hot city such as Athens) – is even less attainable than she is. And at least she is supposed to be irresistibly lovely, her name the very byword for lust. He is just an ordinary, godlike boy.

Many Greek sculptors used a set of ratios to make their statues realistic. But actually the ratios are hyper realistic: no one’s leg-bones are as long as the statues’ appear. And they have muscle groups that mortal men can’t ever achieve: you could go to the gym every day for a year and you wouldn’t acquire an Apollo’s belt like these statues boast. (In related news, don’t Google Apollo’s belt on the train. I’m still apologising to the woman next to me.)

They have muscle groups that mortal men can’t ever achieve:

We’re so used to impossible representations of women that we’ve almost stopped paying attention to them. I can’t remember the last time I even noticed a Disney princess was an implausible shape. But for men, it feels like a more recent shift. To stick with the Greeks: in the Ray Harryhausen films of the 1960s, men could be any shape and still be deemed attractive enough to play the hero. Harry Hamlin didn’t have a six-pack in Clash of the Titans; and as for Nigel Green, playing Hercules in Jason and the Argonauts didn’t mean he had to be in anything like peak condition.

But by the time the 2010 remake of Clash of the Titans came along, Hamlin had been replaced by the uber-beefy Sam Worthington. I much prefer Hamlin’s performance, but Worthington – who has been featured on the cover of Men’s Health magazine – undeniably captured the look of a Greek hero from the ancient Greeks’ own depictions of beauty.

One of the highlights of the exhibition is the Belvedere torso (on loan to the museum from the Vatican). Legend has it that Michelangelo was asked to restore it, but refused because it was too beautiful as it was. The broken body was the inspiration for his vision of God on the ceiling of the Sistine Chapel. The museum has displayed the torso alongside one of the sketches for the finished ceiling, and the crunched abdomen looks unarguably similar.

If women are trying to live up to Aphrodite, a goddess, it turns out that even God has to live up to the idealised Greek male.

• Natalie Haynes’ documentary on the ideals of beauty in Greek sculpture, Body Beautiful, will be on BBC4 on 9 April