Once upon a time, real men really didn't eat quiche.

They did eat prodigious amounts of meat and potatoes: marbled steaks and juicy hamburgers, thick chops and slabs of roast beef – and many still do, despite health risks.

Great big hunks of bloody flesh, however, have never made most women salivate.

Salads with a slice of quiche or slivers of chicken are more appealing. Or maybe a bowl of fruit.

U.S. research shows men prefer meat and protein while women are 22 times more likely to choose chocolate. The difference was far less in Spain – leading researchers to believe the craving for chocolate is actually cultural. But in both countries, 60 per cent of men craved meaty or salty foods while 60 per cent of women craved sweets.

And many more women than men simply don't eat any meat at all.

Statistics show there are about three female vegetarians to every two males. (In the Vegetarian Times some years ago, the president of the North American Vegetarian Society complained that she couldn't find a potential mate who didn't eat meat.)

Man (but not woman) as meat-eater was the subject of a book published in 1990. The Sexual Politics of Meat by Carol Adams was promoted as "a detailed examination of male dominance and meat-eating."

The tendency for men to be into meat and women vegetables begins in childhood.

Results of a 2004 study of more than 1,200 schoolchildren published in the British Journal of Nutrition found "girls liked fruit and vegetables more than boys did. Boys like ... meat, processed meat products and eggs more than girls" – as well as sugary, fatty foods.

Nutritional needs may play a role in these preferences – menstruation, pregnancy, lactation all affect appetite and impose nutritional requirements. But mostly, the differences are attributed to sociological and psychological factors.

Judith Wurtman, director of the Program in Women's Health at the Massachusetts Institute of Technology Clinical Research Center, explains that women naturally have only two-thirds as much serotonin, a key neurotransmitter, as men. This means women are more susceptible to fluctuations that affect mood, appetite and behaviour. Carbohydrates, which women crave, provide the body with amino acid L-tryptophan from which serotonin is synthesized. Women who go on carb-free diets, says Wurtman, suffer from "Atkins attitude" – irritability and bad mood – sooner and more seriously than men.

It's also been suggested that more women are vegetarians because they are more compassionate. That's the other side of the quiche-eating theory: real men don't eat quiche, real women don't eat flesh.

But research also shows women are more health-conscious. Not so keen about meat to begin with, once they become aware of the positive effects of fruits and vegetables and the negative effects of meat, giving up meat isn't difficult.

Different expectations for each gender, as well as self-image, play a large role in eating behaviour and attitudes to food.

In the Health Psychology journal, psychiatrists from Johns Hopkins University School of Medicine wrote that women eat the way they do, and differently from men, because women "experience more dissatisfaction with their body weight and shape than men do ... pressures to be thin are present in early adolescence, as noted by dieting behaviour starting in very young girls."

In other words, even if these girls do prefer the same fatty, sugary foods boys admit to liking – say, a double-chocolate doughnut or half-pint of ice cream – they either won't admit it or they'll avoid those foods.

A couple of years ago, Harvard University held a conference called "Women, Men and Food: Putting Gender on the Table." Panel discussions took place on everything from production to preparation to consumption.

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One revealing demonstration of these gender differences is a University of Illinois study of eating behaviour in a social setting.

Lead researcher Kristen Harrison found that "men who are insecure about their bodies eat more in front of other men, while women who are insecure about their bodies eat less in front of other women."

A man with an "actual body vs. ideal body self-discrepancy," she says, "may be moved to eat even when he is not hungry, just to reassure himself and other men that he is sufficiently masculine."

It's hard to imagine any woman eating just to reassure herself and other women that she's sufficiently feminine.

On the other hand, it's hard to imagine any man, no matter what his "self-discrepancy" issues, craving chocolate, white bread, pastries and noodles only at certain times of the month.

These food cravings, according to a feminist women's health website (fwhc.org), may be caused by increased responsiveness to insulin before menstruation. MIT's Wurtman suggests the menstruating female craves carbohydrates to supply more serotonin to the body to counteract PMS.

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