Can women, with their deep, insatiable craving for chocolate, coexist with men, who long for meat and other high-fat high-protein foods?
Researchers have long suspected that men and women do not crave the same foods. And now several unusually comprehensive studies seem to confirm that their tastes, when it comes to obsessions, really are different.Harmony is over the horizon, however: one just-completed study shows that as men and women age, their cravings become more similar. For those over 65, a frantic raid on the refrigerator might even be a shared experience.
In the past five years, more than 50 papers have been published on cravings, a subject that intrigues and confounds researchers. While scientists are confirming that women tend to crave sweets and men tend to crave meats, there is still no agreement on where cravings come from or what they mean. Although specific cravings could have a nutritional base, most researchers suspect that the desired food is needed more for hormonal or other physiological reasons not yet understood. By learning about cravings, researchers also hope to develop tools for dieters.
"Food cravings are fascinating simply because we don't yet fully understand them," said Dr. Louis Aronne, an expert on obesity at New York Hospital-Cornell Medical Center. "But can we have an addiction to food? The answer is yes, absolutely."
People who feel isolated by their food cravings should know they are not alone. Unless these scores of research papers are wrong, there is really nothing unusual about driving through a blizzard in the middle of the night to find just the right flavor of ice cream.
"The specificity is important because it distinguishes a craving from general hunger," said Dr. Harvey Weingarten, a professor of psychology at McMaster University in Hamilton, Ontario. Others stress that the energy used to acquire the craved food is sometimes greater than the energy provided by the food itself - suggesting that people may be driven by extremely strong pleasure receptors in the brain.
They stress, too, that the desire for specific foods may be based on bodily needs of some kind, while cravings brought on by loneliness or boredom tend to be nonspecific. Indulging nonspecific cravings often produces guilt and depression. When specific cravings - those focused on a particular food - are gratified, however, almost all men and a majority of women in the studies report feeling better.
The monitoring of food cravings is a relatively new science, and it is particularly popular in North America. Most other parts of the world have not studied them in any organized way, although it is known that both sweet and salty foods seem to have universal appeal. Prehistoric cave drawings show cravers who went to inordinate lengths to rob bees of their honey.
In one of the largest studies on food cravings ever undertaken, Weingarten surveyed 1,000 Mc-Mas-ter undergraduates in 1991. Of those, 97 percent of the women acknowledged specific food crav-ings, while only 67 percent of the men did. Among those who had these specific cravings, the sexes were more or less equal: both men and women said they experienced them between five and nine times a month. Women craved chocolate more than any other food.
Men, while noting they sometimes craved chocolate, reported far more frequent longings for steak, hamburger, lasagna and seafood - all high in protein and, in most cases, fat. These desires showed up again in a new study at the Monell Chemical Senses Center, a nonprofit research group in Philadelphia. The study, conducted by Marcia Pelchat, surveyed two groups - those between 18 and 35, and those 65 and older.
In the younger group, women craved high-fat sweets over entrees, 2 to 1. Mostly they craved chocolate, in every form: candy, cake, cookies, ice cream. In the group of young men, the reverse was true. In the older group, men still craved entrees over sweets 2 to 1, but the older women craved sweets and entrees in about equal numbers. They also reported fewer cravings than the younger women.
The results of the Monell study, sponsored by the National Institute on Aging in Bethesda, Md., will be used in an ongoing study of the nutrition of the elderly.
While many researchers simply report the differences they find between men and women, without suggesting the causes, the new work, which is not yet published, gives support to those who argue that women's cravings are hormonally induced and diminish when women pass menopause.
In a new diet book, "Why Women Need Chocolate" (Hyperion, $19.95), Debra Waterhouse, a registered dietician, cites a large number of research references to support her thesis that women crave chocolate and other sweets and fats when their serotonin and endorphin levels are low. These "feel good" amino acids, she says, are activated in the brain by fat and sugar.
They are at their lowest ebb right before menstruation, when the endorphin high produced by ovulation is dropping. The ensuing ennui, crankiness and lethargy are relieved by chocolate and other sugar and fat combinations that release both serotonin and endorphins into the brain.
(A new diet drug, Dexfenfluramine, now being tested for Food and Drug Administration approval, contains endorphin blockers, which knock out the mood-elevating capabilities of fat and sugar, and so making them less likely to be the focus of cravings.)
Waterhouse says that men do not crave the same foods that women do because they are ruled by testosterone, not estrogen, and they need more protein to build and synthesize muscle. Hence, those hankerings for meat, hot dogs and eggs.
The eating patterns of men have not been studied as much as those of women. Most researchers, while indicating some support for the hormonal theory of women's cravings, are not willing to say whether men are seeking protein, fat, or something else altogether in craving things like hamburgers.
"We thought at first it might just be a macho thing," said Dr. Adam Drewnowski, professor and head of the human nutrition program at the University of Michigan. "But then we found that lab animals showed the same food preferences as humans."
Although a food craving could theoretically signal a nutritional deficiency, most people do not report cravings for tofu, carrot sticks or spinach. Rather, they head straight for the high-fat, sweet or salty items that, since childhood, have signaled pleasure. (Children seem to know instinctively that peanut butter and jelly satisfies all three cravings in one fell swoop.)
At the Massachusetts Institute of Technology, Judith Wurtman and Richard Wurtman, professors of brain and cognitive science, have long held that carbohydrates release serotonin and elevate mood in many people, who become tired and irritable on a high-protein, low-carbohydrate diet. And timing, they contend, is important.
Food cravings can strike at any time but they are most often reported in the late afternoon and early evening. They can be "site-induced" (passing by a bakery) or, seemingly, come out of nowhere.
Judith Wurtman has just completed a double-blind study in which two groups of overweight women were given a liquid diet made up of 55 percent carbohydrates, 30 percent protein and 15 percent fat. Although the total components were the same, one group, the more successful dieters, consumed most of their carbohydrates in the late afternoon and early evening - considered the most vulnerable times for food cravers. The other group, who had most of their carbohydrates earlier in the day, and protein later on, tended to cheat with candy bars and sugar cubes in late afternoon.
Sudden, increased desires for sweets and fats may strike those who have recently given up tobacco or alcohol, according to a study done by Susan Schiffman at Duke University. There may indeed be a correlation between drug and alcohol abuse and food cravings. A recent study of undergraduates at the University of Michigan found that students on low-sugar, low-fat diets were at greater risk for cigarette smoking, alcohol and drug abuse.
Drewnowski of the University of Michigan says that what men and women really crave is pleasure. "Fat is what people really want, because it makes you feel good," he said.
Women, he believes, tend to crave fat-and-sugar combinations, while men want fat with protein and fat with salt. "It's not a nutritional need - heaven knows we get enough fat, sugar and salt in our diet," he said. "But in moderation, it's not a bad thing either. Studies now show that pleasure may strengthen the immune system. If you want to release those endorphins, run five miles - or eat some chocolate."