Spicy pumpkin pie, freshly baked cookies, roasted turkey basting in its own juices--these are familiar smells that arouse in us the emotions of a cozy holiday season. But watch out: A single sniff of your favorite food could trigger a feeding frenzy.
"When the turkey is in the oven, the odor prepares not only the brain but the gut waiting to be fed," said Charles J. Wysocki, a biopsychologist and associate member of the Monell Chemical Senses Center in Philadelphia.
"Gastric motility and other physiological phenomena related to feeding can be stimulated by the smell of food," Wysocki said.
Wysocki is a prominent member of the team conducting a Smell Survey for National Geographic magazine. So far, more than 1.5 million people have responded to scratch-and-sniff questionnaires, making it the largest scientific sampling of its kind.
"One of the things found in our survey is that the more intense an odor, the more it evokes a memory," he said. This is one reason people probably overeat during the holidays.
"Walking into a kitchen when bread is baking is a common experience and people can relate to that."
Of all people's senses, smell is the least understood. Scientists are just now beginning to answer some basic questions. Susan Schiffman, a professor of medical psychology at Duke University Medical Center, asked: "Why is it that someone will stuff themselves for a meal and have room for dessert? They are looking for another taste or texture.
"I believe that cognitive cues (such as smell) cause satiety (a sense of feeling full). The problem with Thanksgiving is that we are not going to feel satisfied until we have had everything that we think we are supposed to have."
Does that mean that people who overeat have a better sense of smell than thin people? Do they eat more because the smell, and thus the flavor, is so much more appealing?
"People who are overweight don't necessarily have a better sense of smell than thin people," Schiffman said. "But they are able to identify more types of food with their eyes covered--probably due to the fact that they pay more attention to it. It's a learned thing."
Wysocki agreed that the ability to perceive something as edible "may be an acquired taste." For example, when females were exposed to a spicy essence, 55% of the teen-agers said that they would eat something that smelled similar. The number grew to 73% for adults.
"I am convinced that obesity is a learned behavior, and all the money being spent on the genetic approach is appalling," Schiffman said. "Instead, let's have the flavor without the fat."
That's a nice dream. But can it be done? Schiffman has developed a form of treatment for clinical use called aroma therapy. She uses flavor sprays that impart a certain food flavor (which is mostly smell) and odor on the tongue when sprayed.
"My therapeutic approach is to blast people with the flavors that they crave so they don't eat that much of the food. I take a food, boil off its flavor and bottle it. The low-calorie flavor spray tastes just like the food but only contains 0.1 calories per spray."
Schiffman has developed more than 40 fanciful flavors, including popcorn, pizza and chocolate, to satisfy the hunger pangs of her patients.
Wysocki said he hopes that the procedure will succeed. "A lot of people will benefit. It's non-invasive. But it's new. I have seen no scientific publication of the results so I can't evaluate it yet."
The sprays are currently being marketed through Nutri Systems, a national chain of weight-loss centers. Only time will tell if they will be successful. Meanwhile, Wysocki and Schiffman recommend the following tricks to combat holiday cravings:
- Try "grazing." Enjoy the first few bites, then switch to something else. "According to studies that I have done, the first bite is most pleasant," Schiffman said. "As you eat, each bite tastes a little bit weaker."
- Serve an unusual bill of fare. "Individual variations are something we are just begining to explore," Wysocki said. "There are different acquired tastes, so if you cook something out of the ordinary--something unusual--your guests may be a bit hesitant to binge on it."
- Prepare to diet. "Tell yourself that you don't need these sights and smells," Schiffman said.
It's hard to get away from the delights of holiday cooking. Those of us trying to avoid weight can try abstinence, moderation or binges, accompanied by lots of exercise. "Perhaps the best thing to do is to get a cold," Wysocki joked.