The Globe and Mail

A disease to fight famine?

by Stephen Strauss

The Globe & Mail, Page F8 | January 17, 2004

Feeling hungry, but aren’t tempted to eat? Want instead to start running and keep chugging as long as you can?

In humanity’s hungry past, these twinned responses might have been a vital survival instinct for someone needing the strength to flee from famine. But today the same body response might be anorexia nervosa.

This is the radical thesis that evolutionary psychologist Shan Guisinger put forward in a paper recently published in the journal Psychological Review. She describes the failures of psychological and social theories to explain the reason anorexia strikes so many more women than men – a ratio of 10 to 1 is often cited – and the condition’s strange features.

“Normal” starvation leads to lethargy, depression and increased hunger. Anorexia leads to food refusal, optimism and hyperactivity. Dr. Guisinger argues that the most likely explanation for this is that the genetics of a certain subset of the female population allowed them to lead their families through hungry times.

“When resources were depleted and the tribe despaired, the anorectic’s energy, optimism and grandiosity would mobilize the other members to heroic marches. . . . When a starving tribe reached a new hunting/gathering ground, social pressure exerted by family and friends would in turn have helped the anorectic member(s) to begin eating again,” she says.

Over time, evolution would have favoured women carrying genes for famine-fighting anorexia.

To support her thesis, Dr. Guisinger presents a host of human, animal, biochemical and historical evidence, but she concludes with a caution: “Like obesity, AN was useful then and is deadly now.”

While clearly not the final word on a complicated subject, her analysis allows one to understand the roots of a condition so widespread that common sense says it must have served some larger good in the human evolutionary past.

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The Boston Globe

The Ancestry of Anorexia
Blame biology, not parenting, new theory suggests

by Ellen Ruppel Shell

The Boston Globe | December 30, 2003

Excerpt:

Anorexia, the most lethal of psychiatric disorders, afflicts as many as 1 percent of young women and about a tenth as many men, and casts a Svengalian spell, leading its victims to willingly starve themselves in the midst of plenty. Now, psychologist Shan Guisinger has developed a radical new view of anorexia that she says explains both the bizarre features of the illness — self starvation and hyperactivity — and its resistance to treatment by traditional psychotherapy.

Anorexia, she contends, is not primarily a psychological condition brought on by a troubled childhood — as is often thought — but a disorder based in biology, specifically in the appetite regulation mechanism in the brain. Her theory postulates that anorexics have a biological adaptation to weight loss that causes their bodies to shut off hunger signals, and to ratchet up physical activity, even as their flesh melts away.

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SELF Magazine

No time to lose

by Ginny Graves

SELF Magazine | January 22, 2007

Excerpt:

Even the urge to overexercise can be the result of a chronic lack of food. Studies show that if rats are starved and then maintained at 70 percent of their normal weight, they’ll run up to 20 kilometers a day, says Shan Guisinger, Ph.D., an eating disorders specialist in Missoula, Montana. She believes the manic exercise often seen in patients is an adaptation to famine. “In prehistoric times, when there wasn’t enough food, women had to travel hundreds of miles to find more, so they needed to be able to walk for hours with little to eat,” she says. “When women starve themselves, that hardwired restlessness may kick in.”

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Monitor on Psychology

An evolutionary explanation for anorexia?

by Karen Kersting

Monitor, Vol. 35, No. 4, page 22 | April 2004

Modern anorexia may stem from an adaptation that helped ancient nomadic people find food, according to a recently proposed theory.

An evolutionary instinct that told members of migrating populations to move along when their food supply ran out may be a major contributor to modern anorexia nervosa, according to a new theory.

When food is scarce and starvation begins, most animals and people demonstrate intense hunger, low activity levels and a single-minded search for food. But, when starved, individuals with a genetic tendency toward anorexia feel sated, full of energy and unfazed by starvation–a set of symptoms described in the DSM-IV, says psychologist and Missoula, Mont. private practitioner Shan Guisinger, PhD, in an article published last year in Psychological Review (Vol. 110, No. 4).

“In treating anorexics, I started to wonder if their symptoms could be something that was useful in the past,” Guisinger explains. “When nomadic foragers were starving, it wouldn’t make sense to hunker down and just not eat. If you’re starving it means that there’s no food there, and so you should move on–normal adaptations to starvation would get in the way.”

A problematic adaptation

In the nomadic groups that preceded modern civilization, members who were undeterred by hunger may have become leaders and moved the group to places where food was plentiful, Guisinger says. She argues that this ancient adaptation, which was likely an advantage at the time, today continues to cause anorexia in people who have a genetic predisposition to it.

But whereas food scarcity may have been the original catalyst for anorexia–which kicks in when genetically susceptible people lose 15 percent of their normal body weight through lack of food–intentional dieting related to societal fear of being fat is most often the cause in modern cases, Guisinger says.

“A lot of people have trouble with this theory because they think now, in modern times, when there’s so much food around, why don’t anorexics just start eating again?” she notes. “But the thing about the brain is that it simply responds to body fat levels, making automatic adjustments to hunger and satiety signalers. Evolution is not very elegant sometimes, and adaptations persist where they are not needed. In this case, the adaptation turns off hunger in modern women who diet.”

Making the case through research

Guisinger backs up her theory with evidence from myriad studies pieced together to show that the core symptoms of the disease make adaptive sense. For example, she references research by psychologists Nicholas Mrosovsky, PhD, and David F. Sherry, PhD, that describes food-restriction behavior across species when animals must migrate.

She also cites research by Leo Kron, MD, that illustrates anorexic patients’ tendency toward hyperactivity and compulsions to move. And she points to research by historian Rudolph Bell, PhD, that documents anorexia in medieval people who lost weight through religious fasting. They, too, demonstrated distorted body images, hyperactivity and food refusal.

Though Guisinger’s theory is carefully constructed through her presentation of such evidence, proving an evolutionary cause for a modern illness is tricky, says psychologist Jeanine Cogan, PhD, founder of the Eating Disorders Coalition for Research, Policy and Action. Because Guisinger is looking to the past for causation, proving her hypothesis through research is impossible, she adds.

“She’s made an interpretation that’s compelling,” Cogan says. “And what I found most useful is she raised some excellent points about the physiological and psychological effects of food restriction that may play an important role in causing anorexia.”

Guisinger, who has never published a research article on anorexia before, says she came to her evolutionary conclusion after years of observing patients who wanted to eat, but claimed to be stopped by their bodies. Now, she says the most important step in helping patients is getting their weight back to normal, which, she believes, will turn off their genetically programmed anorexic response. The hypothesis can serve as a basis for cognitive behavioral therapy and for enlisting the aid of loved ones to help keep body weight up, she adds.

“It doesn’t make psychotherapy irrelevant, but it means that more than anything, people are going to need all the help they can get from their therapist, family, doctor and dietician to fight against their body’s signals in, what is to them, a very unnatural way,” she says.

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