‘Wisdom of the Body’ May Determine Food Cravings : Nutrition: Theory points to link between obsessive thoughts for certain foods and biological needs.
All I knew was I wanted it, lusted for it, I had to have it. I’m talking about cold noodles in sesame sauce, a Szechuan specialty available within walking distance of any neighborhood in Manhattan. Unfortunately, I had moved to Washington, and D.C. had never heard of it. I phoned dozens of Chinese restaurants searching for the dish of my dreams. And each time I salivated in hopeful anticipation. On one excursion, my husband and I drove across town, lured by a Chinese restaurateur’s promise. But they weren’t it.
I was experiencing, in common parlance, a food craving. But what I didn’t know at the time was that my obsessive thoughts were accompanied by an internal physiological uproar. While I contemplated the object of my desires, my body was responding with its own urgent appeal. Not only was I salivating expectantly, my pancreas was secreting insulin, my gallbladder was contracting, my heart was beating faster and my senses were razor-sharp.
“Such a reaction is a matter of common experience,” says Shepard Siegel, a professor of psychology at McMaster University in Hamilton, Ontario. As a matter of fact, measurements of the kind of physiological response I had may someday mark the boundary between run-of-the-mill hunger and the special case of cravings.
For now, researchers define a craving only as an intense desire for specific foods or drugs. But many think food cravings include a smorgasbord of biological and psychological events that help the body regulate its intake of nutrients. They’re resurrecting an old nutritional theory, the “Wisdom of the Body” doctrine, to see if it can help explain a link between food cravings and biological needs. If you crave a plate of salty food, is it because your body is deficient in salt?
The theory is attractively simple--probably too simple. But there is growing, though controversial, evidence that the body, speaking a complex language, does express at least a limited wisdom through cravings.
The yearning for a specific food is heightened by both abstinence and the expectation of satisfaction, according to Harvey Weingarten, chairman of the psychology department at McMaster. In fact, research being done at the University of British Columbia indicates that the expectation of food may boost amounts of the neurotransmitter dopamine released in the brain, which makes us feel attentive, fast-thinking and motivated.
Weingarten believes that taste itself may be more addictive than calories or nutrients. “The brain is more interested in what’s happening on the tongue than in the body,” Weingarten says. “If the tongue’s happy, then the brain will be happy. But what the brain thinks is happening on the tongue is affected by what is happening in the rest of the body”--in other words, by your overall nutritional status.
Over the years, evidence for the Wisdom of the Body has arrived almost as regularly as the tides. In a landmark experiment in 1967, University of Pennsylvania psychologist Paul Rozin fed rats a diet deficient in thiamine. Thiamine deficiency results in diminished appetite, yet when the rats were offered a synthetic, thiamine-rich diet, they ate a lot of it. Rozin now believes, however, that the results had more to do with behavioral learning than innate nutritional wisdom.
Among the strongest proponents today of the Wisdom of the Body is Massachusetts Institute of Technology nutritional biochemist Judith Wurtman. Her research demonstrates that carbohydrate cravers feel more alert--and less tired and depressed--after eating high-carbohydrate meals. Carbohydrate craving, she suggests, may be linked to the activity of serotonin, a chemical produced in the brain when sugar or starch is ingested.
Despite such persuasive examples, critics remain unmoved by notions of the Wisdom of the Body. The body doesn’t seem to regulate its hungers as well as it should. Salt, for example, is crucial; we all need it for nerve conduction and smooth muscle function. But even among people with the greatest need for salt, such as patients with adrenal insufficiency, only 15 to 20% report salt cravings.
One problem may be that a modern diet puts us at odds with our biology. Although we are not born with a taste for salt, we quickly develop one. At four to six months of age, we begin to show a decided preference for it--independent of exposure to it. But salt cravings often get out of hand in a world of processed foods.
Fast-food restaurants and junk-food producers can share the blame. Both process foods to exaggerate tastes our bodies are designed to like.
From the American Health and Psychology Today Service-Washington Post Writers Group.
