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Why Stress Tips the Scales

Frayed nerves increase our desire for carbohydrates and fat. And, if the pressure is chronic, we try even harder to hold on to those pounds.


Gale Cordell has never been seriously overweight. In fact, if you ate lunch with her, you would think she was a model eater. But the 57-year-old's ovo-lacto-vegetarian diet degenerates into chaotic, solitary chocolate candy binges when she's upset.

With lots of exercise, Cordell managed to stay a size 6 for most of her adult life. But two years ago a stress fracture curtailed her exercise, and her eating got so out of control that she gained 35 pounds. The depressing weight gain exacerbated the problem. "The more uncomfortable your clothes become, the more stress eating you do," she says.

Cordell is far from alone. Sixty percent of Americans are overweight or obese, and many of them say that their eating habits worsen when they are stressed. Says Gail Frank, a Los Angeles dietitian and spokesperson for the American Dietetic Assn.: "Everybody deals with stress, and food happens to be one of the things they're manipulating. This is the reality in today's world."

Out-of-control eating and weight gain may seem like an irrational, self-destructive response to stress. But food binges and weight gain make biological sense. Under stress, the brain shifts into self-preservation mode, unleashing an array of chemicals and hormones that protect the body from physical danger.

An essential survival mechanism when our ancestors expended lots of energy dodging mountain lions and wrestling with heavy farm equipment, this figh-or-flight response backfires in these sedentary times, when most of our stressors are of the nonphysical sort like IRS deadlines and crashing computers.

Those who have not inherited resilient bodies and minds that can shrug off traffic jams and long lines at the supermarket are more likely to continually enter this self-protective mode. Ultimately, not only do the stress hormones make them hungry, they also make them more likely to pack on the pounds.

Says Dr. Pamela Peeke, a professor of medicine at the University of Maryland who studied the link between weight and stress at the National Institutes of Health: "There is no question that chronic stress can make you fat."

Of course, chronic stress can trigger a number of other medical conditions, including memory loss, hypertension and heart disease. But bariatric physician Dr. Paul Rivas, author of "Turn Off the Hunger Switch," says that unlike those conditions, "emotional" overeating is seen as a character flaw when it leads to excess weight.

Rivas tells his guilt-ridden patients that their compulsion to overeat is a biological flaw, not a character flaw: "It is not because you lack willpower or self-control. You don't even know what you're doing. You're grabbing the food. It's compulsive. You're into a survival mechanism."


A Hormonal Cascade Causes Ravenous Hunger

When this stress response is activated, the brain releases a chemical called corticotropin-releasing hormone, or CRH, that suppresses appetite. The adrenal glands then secrete their powerful fight-or-flight stress hormones, adrenaline and cortisol, which propel sugar into the bloodstream for a short-term energy rush.

After that rush, cortisol sparks ravenous hunger for carbohydrates and fat. "When you're all stressed out, the last thing you reach for is a can of tuna," says Peeke. (She notes that "stressed" is "desserts" spelled backward.)

Worse, we do not give our bodies the downtime they expect after surviving a close call. Instead, we tax our fight-or-flight response by activating it throughout the day as we move from long commutes to demanding bosses to looming day-care pickup deadlines.

The result is prolonged, elevated cortisol levels that spur the release of insulin, the hormone that directs the body to hang on to the fat it has and store more. "If you have lots of stressors, you have lots of periods of rebound insulin secretion. The cumulative effect is a push toward obesity," says Robert Sapolsky, professor of biological and neurological sciences at Stanford University School of Medicine.

Stacking the biochemical deck further, the brain's complex appetite and satiety control system can go haywire under stress. Rivas says that even if his patients were lounging on a Tahiti beach, they would have to fight against their drive to overeat. Most people who overeat when stressed, he says, are genetically prone to an imbalance among at least three of the brain's neurotransmitters, serotonin, dopamine and norepinephrine, which help the body regulate both appetite and mood.

Add ornery children and late mortgages to the equation and, says Rivas, "everything gets worse." For example, when an already short supply of serotonin dwindles further under stress, overeaters launch into desperate forays for sweets because carbohydrates, unlike tuna fish, raise serotonin levels.

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