Remember that deep dive into the peanut butter in the months after
9/11? How about the incredible allure of chocolate when the seemingly
last possibility for anything wonderful has just fizzled in your face?
No, it's not your imagination. You really do crave rich foods when stress
is unrelenting. And a very special and well-meaning collaboration between
your brain and your body makes you do it.
The newly discovered body-brain partnership may shed new light on
so-called atypical depression, the common variant of disorder in which
sufferers eat and sleep excessively and gain weight, in contrast to
garden-variety depression, marked by obvious anxiety, loss of appetite,
insomnia and weight loss. Further, it may explain why antidepressants
commonly cause weight gain.
We seek chocolate, ice cream or napoleans, scientists have
discovered, not just because they taste good. It's actually the body's
attempt to put a brake on the runaway machinery of chronic stress.
The body, it turns out, has a lot of natural wisdom in its
operations. It just wasn't designed to cope with eternal stress, nor with
SubZero freezers or a food shop on every corner.
Here's how the stress system works. Say you're driving on the
freeway, a car cuts you off and you instantly swerve out of the way to
avert disaster. For some time afterwards you're frazzled and jumpy and
your heart feels like it might leap out of your chest.
When you experience sudden danger, your brain instantly signals
your body to turn out a hormone called cortisol. It in turn relays the
message throughout the body to mobilize you for a life-saving response.
Your heart races. You become highly attentive and alert, even vigilant.
Blood vessels constrict and divert the flow of blood from leisurely
processes such as digestion to fast-acting muscles. Metabolism shifts
too, and energy is made rapidly available to your muscles, readying them
But such emergencies don't last forever. Your stress response
system has built into it the capacity to turn itself off. The stress
hormone cortisol acts as its own shut-off signal. When it reaches the
brain it commands the brain to cease the body's production of the
Chronic stress is another story completely, reports a team of
researchers from the University of California at San Francisco. The
system does not turn off. As the situations that give rise to stress
endure, they keep ramping up production of cortisol. You go into an inner
Code Red, marked by anxiety, vigilance, and hyperalertness. Depression is
one consequence of chronic stress.
At the same time, other "nodes" of the long-term stress circuit are
activated. One of them directs you to search for extremely pleasurable
food, notably high-energy bundles of fat and sugar like cream puffs and
chocolate bars. They become comfort foods in every sense of the
Left to its own devices, the long-term anxiety set off by chronic
stress would deplete your energy reserves; you wouldn't survive very
long. But fat- and sugar-laden foods help your body build up reserves and
stay in the game of life.
"One of the functions of stress hormones is to move energy around,"
explains Norman Pecoraro, Ph.D, a postdoctoral fellow on the San
Francisco team. The escalating levels of cortisol released in chronic
stress usher the excess calories straight to your abdomen, where they get
deposited as fat. By virtue of its location, abdominal fat has privileged
access to the liver. That allows it to be quickly mobilized for
Here's the mark of the body's brilliance. Those fat deposits are
absolutely crucial. They send out some metabolic signal that feeds back
to the brain, telling it to shut off the stress response. Those who eat
cream puffs and chocolate are trying to give the body what it needs to
dampen output from their stress system, Pecoraro says. "Eating seems to
ameliorate some of the symptoms of depression, so you won't feel as
anxious. This seems to be the body's way of telling the brain, 'It's OK,
you can relax, you're refueled with high-energy food.'"
He finds it highly provocative that an unwanted side-effect of
antidepressant drugs is obesity. Maybe it's not a side effect but the
main effect. "It raises the question, what's causing the improvement in
mood. Is it a direct action of the serotonin re-uptake inhibitor on the
brain? Or is it an indirect action, a consequence of increased feeding
induced by the drug?
His own guess is that it's a combination of things. "We're not
saying that feeding is everything, but it certainly is important. It's
the coin of the realm. Life just doesn't exist without energy."
The catch is, consumption of calorie-rich foods may make us feel
better and function better, but it's bad for long-term health. The
stresses we face today are not like the eat-or-be-eaten stresses we faced
when our bodies evolved. Nowadays we're up against long-term job
insecurity and romantic rejection. The stress goes on and on and we feel
immobilized by it. The energy reserves do not get used up.
There's a pizza place down the street or the oversize freezer in
the next room that speaks directly to your ongoing need for stress
relief. You keep gaining weight around your abdomen. Unfortunately,
abdominal obesity puts you at specific risk for diabetes and heart
Pecoraro says the discovery of the metabolic signal from fat stores
is the result of 30 years of research by Mary Dallman, Ph.D., on the
stress system. The details were worked out in rats, but the findings,
reported in the Proceedings of the National Academy of Sciences,
"resoundingly" apply to humans.
What's more, he says, they seem to solve the puzzle of atypical
depression. The difference between atypical and typical depression may
lie in the degree to which chronic stress sets off the defensive alerting
system versus the appetitive system. "Atypical depression may be an
attempt to self-medicate with food, to reduce the stress hormone output,
with the unfortunate side effect of visceral obesity."
There is a way out, Pecoraro says. There are other ways to shut off
chronic stress. There's exercise, yoga, meditation, hot baths and, yes,
sex. They all stimulate the same pleasure centers in the brain that make
us seek comfort food. Relaxation techniques may work even earlier in the
process, by reducing the psychological perception of stress in the first
"In the short term, if you're chronically stressed it might be
worth eating and sleeping a little more to calm down, perhaps at the
expense of gaining a few pounds," says Pecoraro. "But seeking a long-term
solution in comfort food—rather than fixing the source of the stress or
your relationship to the source of the stress—is going to be bad for