Some days the refrigerator draws Hannah like a magnet. The 23-year-old pulls open the door, gropes for whatever looks interesting and gorges herself. Several times a week Hannah wolfs down mountains of food, more than 6,000 calories in a single day. Hannah is a binge eater, subject to regular eating attacks and a loss of control over food consumption. In contrast to bulimia sufferers, Hannah makes no effort to counter her caloric intake by vomiting. As a result, she is obese. At five feet, six inches, she weighs 264 pounds. Eating supplies the body with energy and essential nutrients. But that is surely not why Hannah regularly stuffs herself–she continues to eat long after her hunger pangs have subsided. Hannah eats for emotional reasons: when she is sad or anxious, food is her Prozac. Food and emotions are inextricably linked in all of us, but some of us are more emotionally drawn to food than others [see box on page 68]. Hannah and those with similar habits are extreme examples of such a tendency. But research shows that sadness and anxiety can spawn bursts of overeating or indulgence in sweet and fatty foods in large numbers of people who have no defined eating pathology. Scientists can even explain the impulse to snack on crackers or desserts. Carbohydrates and fats are thought to elevate a person’s mood by lowering stress hormone levels–and in the case of carbohydrates, by increasing the amounts of a mood-altering chemical messenger in the brain. The taste of foods can also change a person’s emotional state. Sweet foods are thought to induce the release of pain-relieving substances in the brain and to activate the brain’s pleasure centers in the same way addictive drugs do. Meanwhile the social and physical environment in which we eat often connects food with positive emotions such as relaxation and companionship. By tracing the many links between consumption and contentment, researchers hope to find new ways to combat eating disorders such as Hannah’s as well as patterns of emotional eating that may contribute to obesity. Caloric Comfort Laypeople and doctors alike have long observed that individuals tend to munch more in crisis situations because food helps to cushion negative emotions. The Germans have a word for this, Kummerspeck, literally “grief bacon,” which may date back to observations that World War I widows often put on weight. Today psychologists term this behavior emotional eating. Emotional eaters have a marked tendency to overeat when under some kind of emotional strain. A considerable proportion of overweight people are emotional eaters. In exaggerated form, emotionally driven food consumption can result in binge eating. Psychologist Andrew Hill of the University of Leeds in England and his colleagues confirmed in a 2004 study that negative emotions can provoke eating attacks. The researchers showed a group of 40 obese female binge eaters either a sad or a neutral film and then offered them food in a supposed taste test. The women who watched the sad movie–and felt down as a result–ate considerably more than those who had seen the more upbeat flick, suggesting that negative mood can prompt overeating in susceptible individuals. Emotional eating is not confined to individuals with eating disorders, according to psychologist Georgina Oliver and her colleagues at University College London, who reported in 2000 that anxiety and stress can lead to unhealthy eating habits among more ordinary consumers. The researchers first categorized 68 healthy men and women as emotional or nonemotional eaters using a standard questionnaire. Then they gave a mixed group a stressful task–to prepare a four-minute speech that they claimed would be videotaped and evaluated–while asking a comparison group to relax and listen to a reading. After 10 minutes, all the study participants were served a buffet lunch that included sweet, salty, and bland high- and low-fat foods. The emotional eaters under duress devoured almost twice the weight of energy-dense (sweet and fatty) edibles than did nonemotional eaters in that group. There was no difference, however, in the total amount of food consumed, suggesting that stress can lead some people to choose fattening fare over healthier food. In the group that was not under stress, both emotional and nonemotional eaters showed similar eating patterns. Scientists now have an explanation for this preference: sweet, fatty foods seem to depress the stress response, so people may gorge on them in a subconscious effort to improve their emotional state. A 2003 study by physiologist Mary F. Dallman and her co-workers at the University of California, San Francisco, for example, showed that such diets diminish stress hormones in stressed-out rats. The researchers made the rats tense by confining them in a small clear-plastic cage for three hours a day for five days and then fed one group its usual fare and the other a diet enriched in lard and sugar. They found that the animals that gobbled the richer feed ate more (and got fatter) than those on the regular diet and produced lower amounts of stress hormones, suggesting that the fatty chow helped to reduce stress. Carbohydrates may serve a similar function, perhaps explaining why some people crave, say, bagels and chips when they are depressed or anxious. Some animal and human data from Richard Wurtman, a neuropharmacologist at the Massachusetts Institute of Technology, hint that carbohydrate-rich meals elevate mood by boosting the amount of the amino acid tryptophan in the brain. Tryptophan is used to produce the neurotransmitter serotonin, which is involved in regulation of emotions, among other functions. The serotonin boost that results from higher levels of tryptophan, the theory goes, may elevate mood. Some support for this hypothesis comes from a 1998 study by experimental psychologist C. Rob Markus, now at Maastricht University, and his colleagues at Utrecht University, both in the Netherlands. The researchers gave 48 test subjects–some of whom were particularly prone to stress–meals containing either lots of carbohydrates and little protein or the opposite, plenty of protein and few carbohydrates. They then gave everyone a challenging task: to solve difficult math problems in a noisy room. As expected, the carbohydrate-rich diet elevated blood levels of tryptophan relative to other amino acids (which compete with tryptophan to enter to the brain) much more than the protein-packed fare did. The high-carbohydrate meals also dampened the stress hormone reactions to the math task in the high-stress individuals–but not in the others–far more than the low-carbohydrate food did. Thus, carbohydrates may decrease tension in susceptible people by boosting the brain’s tryptophan dose. People who are not prone to such anxiety, on the other hand, may have enough tryptophan and serotonin in their brain already, the researchers surmised. Sweet Relief Such changes in brain chemistry take time. They occur only after food is digested, its components absorbed into the bloodstream and transported into the brain. The serotonin and stress hormone responses could underlie the slowly growing waistlines of people under chronic stress, but faster mechanisms are undoubtedly at work in cases of impulsive indulgence such as Hannah’s. In anxious, sad or painful moments, a growing body of data suggests, a sweet taste alone is comforting. Classic research by biologist Jacob Steiner of the Hebrew University of Jerusalem shows that a liking for sweet tastes is innate. When Steiner gave newborns a sugar solution, the babies made sucking movements, licked their lips and relaxed their faces, looking satisfied. When given a bitter substance, the babies reacted with disgust, scrunching their eyebrows together and sticking out their tongues. A sweet taste can even ease infant pain and distress. Psychologist Elliott Blass and his co-workers at the University of Massachusetts Amherst found in a 2003 study that tasting a sucrose solution worked as well as sucking a pacifier at diminishing crying in six- and nine-week-old infants. In other work, Blass’s team found that a pacifier dipped in a sugar solution lessened the pain of circumcision far more than an unsweetened pacifier did, based on how much the infants cried and grimaced. The pain suppression from sugar occurs quickly, with the maximum effect achieved in two minutes, about the time it would take a sweet taste to trigger the release of endogenous opiates, natural brain chemicals that heighten pleasure and alleviate pain. Recent work in my laboratory at the University of Wuerzburg in Germany suggests that a sweet taste has similar effects on adults. A 2006 study, for example, co-authored by psychologist Ellen Greimel, demonstrated that adults react to sweet and bitter tastes with facial expressions similar to those of infants. In addition, my colleagues and I have shown that the sweet–and generally scrumptious–taste of chocolate can ease emotional (if not physical) pain in adults. We made volunteers sad by showing them a short film in which a little boy learns of his father’s death. Eating chocolate afterward quickly made the viewers feel better. Why? The chocolate’s effect, we found, depended on its taste–that is, how delicious it was to the taster. The less delicious a person judged the chocolate, the less effect it had on his or her disposition, indicating that chocolate’s taste underlies much of its mood-altering magic. Food as a Drug Chocolate may act in other ways, too. Cocoa contains the stimulants caffeine and theobromine, which alter brain chemistry and might thus contribute to people’s liking for chocolate. Nutrition scientist Hendrik Smit of the University of Bristol in England and his colleagues investigated this hypothesis in a 2005 study. On six mornings the researchers gave 64 people a “novel” drink and a capsule that contained either a nonactive substance or a combination of theobromine and caffeine. They asked the participants each day how much they liked the drink. The people who took the active capsules reported enjoying the drink more and more each day, whereas those who swallowed placebo pills did not develop a similar appreciation for the same liquid. Thus, theobromine and caffeine may independently contribute to a fondness for chocolate. But because these druglike influences require several days to develop, chocolate’s more immediate effects on mood probably stem from sensory factors. Sugar may act like a drug in a different way: by inducing dependency under some circumstances. Princeton University psychologist Bartley Hoebel and his colleagues made rats sugar-dependent by depriving them of food for 12 hours a day and offering them a sucrose solution and chow for the next 12 hours. They repeated this schedule every day for one to four weeks. The cycle of fasting and intermittent sugar availability triggered strong demand: the rats gradually tripled their sucrose intake and learned to binge on the sugar as soon as they received access to it each day. In the brains of the sugar-dependent rats, the researchers detected repeated rises in the amount of the chemical messenger dopamine in part of the brain’s reward system. Such a dopamine increase is characteristic of all addictive drugs; it is thought to elevate mood and, in some cases, produce euphoria. In contrast, no such bingeing or dopamine boosts occurred in control rats that received as much sugar as they wanted or that received no access to sucrose, the researchers reported in 2005. The addictive qualities of sugar are apparently a result of its taste, because they do not depend on digestion. In a 2006 experiment conducted by Hoebel’s team, the dopamine rush occurred in sugar-dependent rodents even when the sugar they drank was immediately removed from the stomach by an implanted fistula. Making Connections But physiology cannot fully explain food’s power over our feelings. Some of our emotional connections to food grow out of life experience. At birth, for example, eating is conflated with love and a sense of safety in all mammalian species. During nursing, a baby feels a sense of closeness that helps to cement critical bonds with its mother, linking food to a feeling of equilibrium. Later in life, people share meals with friends and family, tying together food with the growth of friendship and love. They also prepare cuisine for celebrations and romantic picnics. In this way, food becomes associated with intense positive emotions such as relaxation, warmth and contentment. Such connections exist in virtually all of us. Nobody knows, however, what causes a subset of humanity to seek solace in food in the absence of hunger. German psychiatrist Hilde Bruch suggested that part of the answer could be found in a person’s upbringing. The more frequently a mother offers food to her child when he or she is upset but not actually hungry, Bruch hypothesized, the more apt that child will be to deal with negative emotions by eating. Genes are probably also critical. After all, people are born with different taste sensitivities, particularly with regard to bitter substances [see “Bitter Could Be Better,” by Stefanie Reinberger; Scientific American Mind, June/July 2006]. That said, no one yet knows how a more (or less) responsive palate might influence emotional eating behavior or how inborn features of brain chemistry might affect the extent to which emotions influence eating. No matter its origins, emotional eating behavior such as Hannah’s will likely require an emotion-centered solution. Stanford University psychologist Christy Telch and her colleagues tested such a strategy on 44 women with binge-eating disorder. Some of the women received no treatment, whereas others underwent so-called dialectical-behavior therapy (DBT), in which they learned to deal with negative emotions in ways other than by eating. Over 20 sessions, a therapist explained the genesis and role of emotions and taught the women strategies for coping with stress, among other tactics. The therapy seemed to work: by the end of the experiment, the women who had received DBT were having many fewer eating attacks than the control subjects, and 89 percent of those treated had stopped binge eating. Six months later 56 percent of the treated women were still abstinent, the researchers reported in 2001. From this therapy, Hannah learned to take charge of her negative emotions by relaxing and writing them down. Her eating attacks gradually became less frequent, and she is in far better emotional and physical shape today.
Hannah is a binge eater, subject to regular eating attacks and a loss of control over food consumption. In contrast to bulimia sufferers, Hannah makes no effort to counter her caloric intake by vomiting. As a result, she is obese. At five feet, six inches, she weighs 264 pounds.
Eating supplies the body with energy and essential nutrients. But that is surely not why Hannah regularly stuffs herself–she continues to eat long after her hunger pangs have subsided. Hannah eats for emotional reasons: when she is sad or anxious, food is her Prozac.
Food and emotions are inextricably linked in all of us, but some of us are more emotionally drawn to food than others [see box on page 68]. Hannah and those with similar habits are extreme examples of such a tendency. But research shows that sadness and anxiety can spawn bursts of overeating or indulgence in sweet and fatty foods in large numbers of people who have no defined eating pathology.
Scientists can even explain the impulse to snack on crackers or desserts. Carbohydrates and fats are thought to elevate a person’s mood by lowering stress hormone levels–and in the case of carbohydrates, by increasing the amounts of a mood-altering chemical messenger in the brain. The taste of foods can also change a person’s emotional state. Sweet foods are thought to induce the release of pain-relieving substances in the brain and to activate the brain’s pleasure centers in the same way addictive drugs do.
Meanwhile the social and physical environment in which we eat often connects food with positive emotions such as relaxation and companionship. By tracing the many links between consumption and contentment, researchers hope to find new ways to combat eating disorders such as Hannah’s as well as patterns of emotional eating that may contribute to obesity.
Caloric Comfort Laypeople and doctors alike have long observed that individuals tend to munch more in crisis situations because food helps to cushion negative emotions. The Germans have a word for this, Kummerspeck, literally “grief bacon,” which may date back to observations that World War I widows often put on weight.
Today psychologists term this behavior emotional eating. Emotional eaters have a marked tendency to overeat when under some kind of emotional strain. A considerable proportion of overweight people are emotional eaters. In exaggerated form, emotionally driven food consumption can result in binge eating.
Psychologist Andrew Hill of the University of Leeds in England and his colleagues confirmed in a 2004 study that negative emotions can provoke eating attacks. The researchers showed a group of 40 obese female binge eaters either a sad or a neutral film and then offered them food in a supposed taste test. The women who watched the sad movie–and felt down as a result–ate considerably more than those who had seen the more upbeat flick, suggesting that negative mood can prompt overeating in susceptible individuals.
Emotional eating is not confined to individuals with eating disorders, according to psychologist Georgina Oliver and her colleagues at University College London, who reported in 2000 that anxiety and stress can lead to unhealthy eating habits among more ordinary consumers. The researchers first categorized 68 healthy men and women as emotional or nonemotional eaters using a standard questionnaire. Then they gave a mixed group a stressful task–to prepare a four-minute speech that they claimed would be videotaped and evaluated–while asking a comparison group to relax and listen to a reading.
After 10 minutes, all the study participants were served a buffet lunch that included sweet, salty, and bland high- and low-fat foods. The emotional eaters under duress devoured almost twice the weight of energy-dense (sweet and fatty) edibles than did nonemotional eaters in that group. There was no difference, however, in the total amount of food consumed, suggesting that stress can lead some people to choose fattening fare over healthier food. In the group that was not under stress, both emotional and nonemotional eaters showed similar eating patterns.
Scientists now have an explanation for this preference: sweet, fatty foods seem to depress the stress response, so people may gorge on them in a subconscious effort to improve their emotional state. A 2003 study by physiologist Mary F. Dallman and her co-workers at the University of California, San Francisco, for example, showed that such diets diminish stress hormones in stressed-out rats. The researchers made the rats tense by confining them in a small clear-plastic cage for three hours a day for five days and then fed one group its usual fare and the other a diet enriched in lard and sugar. They found that the animals that gobbled the richer feed ate more (and got fatter) than those on the regular diet and produced lower amounts of stress hormones, suggesting that the fatty chow helped to reduce stress.
Carbohydrates may serve a similar function, perhaps explaining why some people crave, say, bagels and chips when they are depressed or anxious. Some animal and human data from Richard Wurtman, a neuropharmacologist at the Massachusetts Institute of Technology, hint that carbohydrate-rich meals elevate mood by boosting the amount of the amino acid tryptophan in the brain. Tryptophan is used to produce the neurotransmitter serotonin, which is involved in regulation of emotions, among other functions. The serotonin boost that results from higher levels of tryptophan, the theory goes, may elevate mood.
Some support for this hypothesis comes from a 1998 study by experimental psychologist C. Rob Markus, now at Maastricht University, and his colleagues at Utrecht University, both in the Netherlands. The researchers gave 48 test subjects–some of whom were particularly prone to stress–meals containing either lots of carbohydrates and little protein or the opposite, plenty of protein and few carbohydrates. They then gave everyone a challenging task: to solve difficult math problems in a noisy room.
As expected, the carbohydrate-rich diet elevated blood levels of tryptophan relative to other amino acids (which compete with tryptophan to enter to the brain) much more than the protein-packed fare did. The high-carbohydrate meals also dampened the stress hormone reactions to the math task in the high-stress individuals–but not in the others–far more than the low-carbohydrate food did. Thus, carbohydrates may decrease tension in susceptible people by boosting the brain’s tryptophan dose. People who are not prone to such anxiety, on the other hand, may have enough tryptophan and serotonin in their brain already, the researchers surmised.
Sweet Relief Such changes in brain chemistry take time. They occur only after food is digested, its components absorbed into the bloodstream and transported into the brain. The serotonin and stress hormone responses could underlie the slowly growing waistlines of people under chronic stress, but faster mechanisms are undoubtedly at work in cases of impulsive indulgence such as Hannah’s.
In anxious, sad or painful moments, a growing body of data suggests, a sweet taste alone is comforting. Classic research by biologist Jacob Steiner of the Hebrew University of Jerusalem shows that a liking for sweet tastes is innate. When Steiner gave newborns a sugar solution, the babies made sucking movements, licked their lips and relaxed their faces, looking satisfied. When given a bitter substance, the babies reacted with disgust, scrunching their eyebrows together and sticking out their tongues.
A sweet taste can even ease infant pain and distress. Psychologist Elliott Blass and his co-workers at the University of Massachusetts Amherst found in a 2003 study that tasting a sucrose solution worked as well as sucking a pacifier at diminishing crying in six- and nine-week-old infants. In other work, Blass’s team found that a pacifier dipped in a sugar solution lessened the pain of circumcision far more than an unsweetened pacifier did, based on how much the infants cried and grimaced. The pain suppression from sugar occurs quickly, with the maximum effect achieved in two minutes, about the time it would take a sweet taste to trigger the release of endogenous opiates, natural brain chemicals that heighten pleasure and alleviate pain.
Recent work in my laboratory at the University of Wuerzburg in Germany suggests that a sweet taste has similar effects on adults. A 2006 study, for example, co-authored by psychologist Ellen Greimel, demonstrated that adults react to sweet and bitter tastes with facial expressions similar to those of infants. In addition, my colleagues and I have shown that the sweet–and generally scrumptious–taste of chocolate can ease emotional (if not physical) pain in adults.
We made volunteers sad by showing them a short film in which a little boy learns of his father’s death. Eating chocolate afterward quickly made the viewers feel better. Why? The chocolate’s effect, we found, depended on its taste–that is, how delicious it was to the taster. The less delicious a person judged the chocolate, the less effect it had on his or her disposition, indicating that chocolate’s taste underlies much of its mood-altering magic.
Food as a Drug Chocolate may act in other ways, too. Cocoa contains the stimulants caffeine and theobromine, which alter brain chemistry and might thus contribute to people’s liking for chocolate. Nutrition scientist Hendrik Smit of the University of Bristol in England and his colleagues investigated this hypothesis in a 2005 study. On six mornings the researchers gave 64 people a “novel” drink and a capsule that contained either a nonactive substance or a combination of theobromine and caffeine. They asked the participants each day how much they liked the drink.
The people who took the active capsules reported enjoying the drink more and more each day, whereas those who swallowed placebo pills did not develop a similar appreciation for the same liquid. Thus, theobromine and caffeine may independently contribute to a fondness for chocolate. But because these druglike influences require several days to develop, chocolate’s more immediate effects on mood probably stem from sensory factors.
Sugar may act like a drug in a different way: by inducing dependency under some circumstances. Princeton University psychologist Bartley Hoebel and his colleagues made rats sugar-dependent by depriving them of food for 12 hours a day and offering them a sucrose solution and chow for the next 12 hours. They repeated this schedule every day for one to four weeks. The cycle of fasting and intermittent sugar availability triggered strong demand: the rats gradually tripled their sucrose intake and learned to binge on the sugar as soon as they received access to it each day.
In the brains of the sugar-dependent rats, the researchers detected repeated rises in the amount of the chemical messenger dopamine in part of the brain’s reward system. Such a dopamine increase is characteristic of all addictive drugs; it is thought to elevate mood and, in some cases, produce euphoria. In contrast, no such bingeing or dopamine boosts occurred in control rats that received as much sugar as they wanted or that received no access to sucrose, the researchers reported in 2005.
The addictive qualities of sugar are apparently a result of its taste, because they do not depend on digestion. In a 2006 experiment conducted by Hoebel’s team, the dopamine rush occurred in sugar-dependent rodents even when the sugar they drank was immediately removed from the stomach by an implanted fistula.
Making Connections But physiology cannot fully explain food’s power over our feelings. Some of our emotional connections to food grow out of life experience. At birth, for example, eating is conflated with love and a sense of safety in all mammalian species. During nursing, a baby feels a sense of closeness that helps to cement critical bonds with its mother, linking food to a feeling of equilibrium.
Later in life, people share meals with friends and family, tying together food with the growth of friendship and love. They also prepare cuisine for celebrations and romantic picnics. In this way, food becomes associated with intense positive emotions such as relaxation, warmth and contentment.
Such connections exist in virtually all of us. Nobody knows, however, what causes a subset of humanity to seek solace in food in the absence of hunger. German psychiatrist Hilde Bruch suggested that part of the answer could be found in a person’s upbringing. The more frequently a mother offers food to her child when he or she is upset but not actually hungry, Bruch hypothesized, the more apt that child will be to deal with negative emotions by eating.
Genes are probably also critical. After all, people are born with different taste sensitivities, particularly with regard to bitter substances [see “Bitter Could Be Better,” by Stefanie Reinberger; Scientific American Mind, June/July 2006]. That said, no one yet knows how a more (or less) responsive palate might influence emotional eating behavior or how inborn features of brain chemistry might affect the extent to which emotions influence eating.
No matter its origins, emotional eating behavior such as Hannah’s will likely require an emotion-centered solution. Stanford University psychologist Christy Telch and her colleagues tested such a strategy on 44 women with binge-eating disorder. Some of the women received no treatment, whereas others underwent so-called dialectical-behavior therapy (DBT), in which they learned to deal with negative emotions in ways other than by eating. Over 20 sessions, a therapist explained the genesis and role of emotions and taught the women strategies for coping with stress, among other tactics.
The therapy seemed to work: by the end of the experiment, the women who had received DBT were having many fewer eating attacks than the control subjects, and 89 percent of those treated had stopped binge eating. Six months later 56 percent of the treated women were still abstinent, the researchers reported in 2001. From this therapy, Hannah learned to take charge of her negative emotions by relaxing and writing them down. Her eating attacks gradually became less frequent, and she is in far better emotional and physical shape today.
