01/20/2011 04:12 pm ET Updated May 25, 2011

Understanding Oprah's Mac-and-Cheese Binge From an Evolutionary Perspective

On Monday, Oprah Winfrey told Piers Morgan on his new show that following the box-office bust of her 1998 film "Beloved," she sank into a "massive, depressive macaroni-and-cheese eating tailspin" and downed some "30 pounds' worth" of the salty, fatty, carb-loaded stuff.

Excessive? Yes. But logical, even -- in an extreme way -- life-preserving? Absolutely.

That we reach for greasy gloppy goodies when we're stressed (in Winfrey's case, to the point of depression) is an evolutionary necessity, wired into our brains to ensure our survival as a species. But these days, with such "comfort food" so accessible, the circuit has gone haywire. Winfrey, after all, had simply to ask her chef to whip up a massive batch of the cheesy goo.

Since at least the mid-1970s, scientists have been showing that cortisol, our primary stress hormone, activates the same reward system in the brain as cocaine, heroin and other drugs of abuse. True, the degree of activation is different, but the process is the same. Both cortisol and addictive drugs stimulate neurons in a part of the brain called the ventral tegmental area, which sits atop the brainstem, to release the neurotransmitter dopamine. The dopamine then zips via nerve fibers over to the nucleus accumbens, the so-called pleasure center of the brain. The information, "Ahh, pleasure," is then relayed to the prefrontal cortex, where it makes its way into consciousness.

Mind you, the dopamine itself is not the reward. Rather, it sparks the motivation to do the work to get the reward. The good feelings are ones of delicious anticipation. Dopamine supercharges wanting.

What we want during stress, scientists say, depends on context. The reward just has to be palatable, a natural reinforcer. Studies have shown that if a rat is stressed and a hunk of pork fat and regular chow are both within reach, it'll make a beeline for the pork fat. If cocaine is available at the push of a lever, it'll go for that. If a running wheel is the only game in town, it'll exercise its little legs off.

The food-as-drug comparison goes even further. Sweet, high-fat foods increase the release of endogenous opioids, or endorphins -- naturally occurring brain chemicals that also activate the brain's reward system. The opioids, in turn, increase the dopamine dump. The two together spur the intake of even more sweet, high-fat foods, which then increases the release of opioids, which...

It's a cycle remarkably similar to that of drug addiction. No wonder Winfrey couldn't stop at a mere 15 or 20 pounds of her mac-and-cheese fix.

Eating because of stress makes evolutionary sense beyond its tranquilizing properties. Cortisol, after all, exists to save our skins -- at least, that was its reason for being back when we were hunter-gatherers attempting, say, to spear a moose for dinner. Cortisol sparks the release of glucose, the simplest sugar, into the bloodstream from the liver and muscles. The glucose release ensured that the hunter-gatherer had plenty of accessible energy (calories) to either slay the moose or flee to safety -- and also that he had plenty of glucose to replenish energy stores once the stressor had passed. Moose carved up and hunks of meat over shoulder? Time to eat again.

The problem is, these days most of our stressors are not of the short-lived physical kind; they bubble up and take hold in our heads: when we're in traffic, or obsessing about money, or plowing through mountains of work, or caring for aging parents -- or, in Oprah Winfrey's case, when "Chucky" trounced "Beloved." We don't need that extra glucose spurt, nor do we need to replenish glucose stores once the stressor has passed, but our brain and body don't know that. And so we eat, and the added fat goes right to our belly, the worst place for it to be.

We can break the cycle. Here are two ways to start:

Learn to eat mindfully. Indiana State University's Jean. L. Kristeller, Ph.D., co-founded an entire center to educate people about mindful eating. The site includes everything from "Principles for Mindful Eating" to downloadable MP3s of presentations on topics such as "Unintentional Eating" and "Different Types of Hunger." With Kristeller's method, people first rate their level of hunger and fullness when they're ready to eat, then learn how to savor the food for part of the meal. "The process slows down eating in a manageable way and increases enjoyment," says UCSF health psychologist Elissa Epel, Ph.D., who studies the relationship between stress and obesity. "Even a few moments of being fully aware can change the quality -- and the size! -- of a meal."

Sever the stressed-digest connection. Partly what drives us to reach for, say, a boatload of mac-and-cheese when we're stressed is the memory that the stuff made us feel better last time. So rather than reaching automatically for your particular brand of comfort food, develop a new association -- to something that makes you feel better and is good for you -- before the next stressor strikes. Remember: Many activities can kick off the reward circuit. Me? I high-tail it to my swanky club, where I can watch movies on a giant flat-screen TV while I power away on the elliptical -- a wonderful treat, given that I own just a tiny box of a TV sans the cable to even get movies.

This article was adapted from Stress Less: The New Science That Shows Women How to Rejuvenate the Body and the Mind, by Thea Singer (Hudson Street Press, 2010).


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