Ask Alison McCormick to rate how stressful the past year and a half has been, and, on a scale of 1 to 10, she’d have to give it a 9 3/4. Easy.
First, the grandmother she’d been closest to passed away. Then she spent several months caring for her mother-in-law, who’d had a stroke. While all this was happening, McCormick, a fourth-grade teacher in Ventura, Calif., was having disagreements with her job-share partner and ended up looking for a new position. Finally, after a difficult search, she landed a new teaching job she loves — just in time for the after-school arrangements she’d made for her own young children to fall apart.
“If it wasn’t one thing, it was another," says McCormick, 39. “And in the midst of it all, I gained over 10 pounds."
The link between stress and weight gain has long been known — at least to women like McCormick, who can relate tales of how they put on extra pounds during trying times. But in recent years, science also has made a case for the stress-weight gain connection, says Pamela Peeke, MD, MPH, a former research fellow at the National Institutes of Health. Now an assistant clinical professor of medicine at the University of Maryland School of Medicine, Peeke is the author of a recent book, Fight Fat After Forty. In it, she makes the case that stress likely does play a central role in weight gain by affecting both appetite and the way the body stores fat and offers a fairly simple antidote to the problem. “Exercise," she says, “is the ultimate neutralizer of the effects of stress."
It’s Only Natural: Our Innate Response to Stress
Like many people, McCormick has often rewarded herself with food after a stressful day. “I would say to myself, ‘I deserve ice cream,'" McCormick says. We usually blame such a response on psychology — after all, eating is one way we nurture ourselves. But Peeke argues that there also may be a physiological reason. She calls it the “stew and chew" response.
When we experience something stressful, our brains release a substance known as corticotropin-releasing hormone (CRH), which puts the body on alert and sends it into “fight or flight" mode. As the body gears up for battle, the pupils dilate, thinking improves, and the lungs take in more oxygen. But something else happens as well: Our appetite is suppressed, and the digestive system shuts off temporarily. CRH also triggers the release of the hormones adrenaline and cortisol, which help mobilize carbohydrate and fat for quick energy. When the immediate stress is over, the adrenaline dissipates, but the cortisol lingers to help bring the body back into balance. And one of the ways it gets things back to normal is to increase our appetites so we can replace the carbohydrate and fat we should have burned while fleeing or fighting.
“But when was the last time you responded to stress with such physicality?" Peeke asks. In today’s modern world, this elegant survival mechanism may be an anachronism that causes the body to refuel when it doesn’t need to.
Yet, it’s not just quick, unsettling episodes that can prove problematic, says Peeke. Feeling stressed-out over a long period of time may be fattening, too: Sustained stress keeps cortisol, that cursed hunger promoter, elevated and that keeps the appetite up, too.
And there’s another factor as well. If stress and cortisol levels stay high, so will insulin levels, says Robert M. Sapolsky, PhD, a professor of biological sciences and neuroscience at Stanford University. “The net effect of this will be increased fat deposition in a certain part of the body."
And that body part generally is the waistline. A recent study conducted by researchers at Yale University and published in the September 2000 issue of Psychosomatic Medicine compared 30 women who stored fat primarily in their abdomens with 29 women who stored it mostly in their hips. They found that the women with belly fat reported feeling more threatened by stressful tasks and having more stressful lives. They also produced higher levels of cortisol than the women with fat on their hips. And that, the authors reasoned, suggests that cortisol causes fat to be stored in the center of the body.
Peeke’s own work points to another reason stressed-out women may store fat in the abdomen. “Our research has shown that the fat cells deep in the belly are richer in stress hormone receptors than fat cells elsewhere in the body," Peeke says. “And it makes sense that fat would be stored in the abdomen, close to the liver, where it can be quickly accessed for conversion into energy."
That may not only be distressing for some women, but dangerous: A Harvard Medical School study published in the December 1998 issue of The Journal of the American Medical Association found that abdominal fat was strongly associated with an increased risk of coronary heart disease.
Why exercise helps
The idea that exercise is a crucial tool in the fight against weight gain isn’t new. It does, after all, burn calories. But Peeke contends that exercise also is beneficial because it helps cut stress, which in turn helps you keep weight off.
“During vigorous exercise, the body secretes biochemicals called beta endorphins, which calm you down and decrease the levels of stress hormones in your body," she says. How much exercise does it take? That depends, Peeke says. “Some people need more vigor than others," she says, “but for some, even a vigorous 10-minute walk will work."
Exercise may reduce stress in another way. “Just getting up and moving for five minutes is helpful," says Peeke, “because you have distracted yourself from what’s causing you stress and allowed your quiescent body to move and stretch and awaken."
Of course, five minutes of exercise may help, but it won’t do much if you also hope to burn some calories. For a bigger payoff, Peeke suggests 45 minutes of exercise every day, even if you break it up into 15-minute sessions.
For Alison McCormick, the idea of a scientific link between exercise, stress, and weight gain wasn’t very surprising. “I intuitively knew that exercise would help me feel less stressed out, and now that I’m running two miles three times a week, I do feel calmer," she says. And, by the way, she’s lost 7 pounds.
Daryn Eller is a freelance writer in Venice, Calif. Her work has appeared in Health, Fitness, and many other publications.