Stress and Cravings


Stress and Cravings

When the going gets tough, the tough (and not-so-tough) often get hungry. Why that happens has been a mystery.

Although researchers have had clues that there might be some scientific basis for the notion of "comfort food," the precise link between stress and eating has been fuzzy.

Now, scientists have developed a model for a biological link between stress and the drive to eat: Food with lots of sugar, fat and calories appears literally to calm the body's response to chronic stress.

In addition, research indicates stress hormones encourage formation of fat cells, particularly the kind that are the most dangerous to health. That may be at least one reason why obesity rates are skyrocketing.

"In highly industrialized countries, people do apparently seem to feel more stressed - more under the gun," said Mary F. Dallman, a professor of physiology at the University of California at San Francisco, who outlined her theory in a paper to be published in a coming issue of the Proceedings of the National Academy of Sciences. "And they certainly are eating a lot more."

The new theory has been drawing praise from other scientists since it was posted on the Internet this month.

"It's an important new model," said Alan G. Watts, a professor of neuroscience at the University of Southern California. "She's brought together under one roof two parallel processes. This is the first time anybody's been able to put together a united theory on stress and energy metabolism. It presents a new way of thinking about this."

While the relationship between stress and eating is driven by a complex mixture of emotional, psychological, social and physiological factors, the new research does appear to explain puzzles that have long baffled researchers, said Elissa S. Epel, an expert on stress, eating and fat at the University of California at San Francisco.

Scientists have long known that during times of stress, parts of the brain emit a chemical signal called corticotropin-releasing factor (CRF), which in turn causes the adrenal gland to pump out large amounts of hormones known as adrenal corticosteroids, including cortisol. These "stress hormones" flood the body, producing a wide array of effects designed to get ready to flee or fight: The immune system gets damped down. Alertness increases. Heart rate quickens. Activity jumps.

During acute stress - a car accident, an argument - a feedback system kicks in and shuts down this response fairly quickly. But during chronic stress, the system keeps going, caught in a vicious cycle.

To examine the relationship between chronic stress and food, Dallman and her colleagues conducted a series of experiments with rats, which are considered good models for how the same systems work in people. The researchers studied levels of stress hormones, brain activity and chemical signals, as well as fat distribution in the rats' bodies, comparing animals experiencing acute and chronic stress induced by exposure to cold or being restrained. The researchers also manipulated some animals' stress hormone levels by removing their adrenal glands, administering stress hormones or injecting them with the chemical signals that produce stress hormones.

When the rats were under chronic stress and had high levels of stress hormones coursing through their bodies, they became very active. They ingested large amounts of high-calorie lard, eschewing their normal feed, and drank prodigious amounts of sugar water. They ignored water containing saccharin, even though it tasted equally sweet. This, in turn, tended to make the rats develop deposits of fat cells in their abdominal areas. In humans, fat that gathers around the waist tends to increase the risks for various health problems.

"When you've got animals in the wild, or people in underdeveloped countries facing, say, a drought, they will turn on their adrenal corticosteroid system. That will make them run to get food and then they get food and eat and create stores of fat, which they need to do," Dallman said.

"It works beautifully when there isn't plenty of food around," she said. "But when there is plenty of food around, like in our society, where there's a McDonald's on every corner, it gets us into deep doo-doo, because this is the kind of fat that if it stays on is very bad for you. It's associated with diabetes and heart disease and stroke."

The fat cells, in turn, appear to send signals back to the brain, shutting down the production of stress hormones, which makes animals - and people - feel better and relax until they burn off those fat deposits. After ingesting high-sugar, high-fat diets, and developing fat deposits, the levels of CRF in the laboratory rats dropped.

But losing weight apparently reactivates the stress response system, starting the whole process again, said Norman Pecoraro, who works with Dallman.

"You're losing that metabolic signal to the brain that's calming things down. So you're removing that yourself by dieting. So one thing that's going to happen is that you'll feel more anxious and won't feel as good and you'll mount this compulsion system to go get the goodies," Pecoraro said.

Other researchers said the work needs to be followed up with additional studies in animals and people.

"I think it's a fascinating new insight into this thing we refer to as comfort foods," said Bruce S. McEwen, a professor of neuroendocrinology at the Rockefeller University in New York. "Often what we call old wives' tales turn out to have a scientific basis, and this seems to be the beginning of understanding this old wives' tale."

If scientists can identify some of the chemical signals involved in the feedback loop of eating, fat and stress, and design drugs to block them, that could lead to new treatments for obesity, McEwen said. "One might be able to find a drug that helps to calm this system down, so to speak."

Dallman hopes the new understanding might help people control their appetite without drugs. "It seems to me that when I know there's a reason for something that's happening," she said, "then maybe I can have more control over it."

Book says stress No. 1 health issue

"Live your life as if you were dying."

This is drastic advice that may just save your life, say Toronto's Penny Kendall-Reed and Dr. Stephen Reed. Their new book, The Complete Doctor's Stress Solution (Robert Rose, $24.95), offers medical insight into the effects of stress and routes to a longer, disease-free life.

Recognizing a stress-driven life before it turns into stress- related disease is key. Turning back time gets harder with each headache, rash or occasion of road rage.

"Ninety per cent of visits to doctors are stress-related. The problem will have a different name but the root is stress," says Reed, a Toronto surgeon. Both he and Kendall-Reed, a naturopathic doctor, believe stress will be the dominant health problem of the 21st century.

The most visible consequences are stroke and heart attack. However, Kendall-Reed points out that infertility, weight gain, digestive problems, allergies, depression and diabetes are also part of the big picture. The book backs this up with cause-and-effect statistics and information.

Recognizing the problem comes first. Quick stress leads to palpitations, short-term memory loss, a rise in blood pressure and sleep deprivation. "You know it is short-term stress if the symptoms go away in 24 hours," says Reed. Continual weight gain, bowel dysfunction, frequent colds and worsening of allergies indicate long- term stress. "The body is simply not getting a time out."

Time outs are easy but, in a society that rewards multi-tasking, "going the extra mile," working extra hours and overachievement even in small children, breaking the pattern or recognizing you are in one, is a challenge.

"Stress destabilizes the way the body functions," says Kendall- Reed, who explains that serious dysfunction needs long-term help but says people can start to rescue themselves with simple steps.

n Stabilize blood sugar. "Eat protein at every meal and have protein for snacks." Meat, fish or cheese, a protein shake and a handful of nuts and dried fruit qualify.

n Breathe. "Four or five deep breaths when you wake up, sit down at your computer, or sit in a traffic jam." Putting red sticky dots on common things such as watch faces and mirrors will remind you to take a deep breath when you see one.

n "Put a drop of lavender oil under your nose when you go to bed, especially if you often wake between two and four a.m."

n Exercise but don't push to increase limits. Reasonable exercise is 30 minutes three or four times a week.

n "Take anti-stress natural supplements." Kendall-Reed mentions magnolia bark extract, multi-B vitamins, drinking green tea.

These suggestions are from a de-stress program in the book, which has the subtitle: Understanding, Treating, and Preventing Stress and Stress-Related Illnesses. The information takes time to absorb but the most important point is also the simplest. Kendall-Reed: "Diet and exercise alone aren't enough. You can't eat well and work out and still go, go, go."

So, occasionally, pull yourself up short and imagine being on your deathbed. Then fill in the end of this sentence: "I wish I'd . . ." Odds are it won't be ". . . spent more time at the office."