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Anorexia Nervosa

Understanding Anorexia Nervosa

What causes people to starve themselves?

Anorexia nervosa, a disorder that distorts its victims' body image and causes them to steadily starve themselves, is among the most dangerous mental health conditions. Four percent of people with anorexia die due to the disorder, and 20 percent die as a result of complications, such as suicide or heart problems.

To the outsider, anorexia can seem strange. After all, the human desire to survive coupled with the overwhelming discomfort of hunger might make it seem like anorexia should never happen. We live in a world obsessed with beauty, though, and our culture equates beauty with being thin. For some people, this can kick the desire to lose weight into overdrive, and about one percent of the female population eventually develops an eating disorder.

But society's fixation on image doesn't explain the full picture, since most people never develop an eating disorder. Ongoing research is beginning to uncover new explanations for anorexia, and this information might eventually lead to better methods for prevention. A Psychiatric Times piece by Dr. Walter H. Kaye attempts to uncover the variable causes of anorexia.

The Role of Genetics

Like most mental health conditions, anorexia likely has a genetic component. People who have anorexia are more likely to have a parent or family member with the disorder. Of course, this could also indicate environmental causes for the disorder, and environment certainly plays a role. A mounting body of research, though, suggests genetic underpinnings to the disorder. One recent study linked anorexia to a gene that codes for an enzyme that plays a role in cholesterol metabolism. The authors of that study argue that this could mean anorexia is somehow linked to disruptions in how the body processes cholesterol.

It might also be that it's not so much anorexia that's genetically influenced, but personality traits that tend to lead to the disorder. Personality traits such as perfectionism, obsessiveness, and anxiety are all associated with anorexia nervosa, and these traits tend to appear in early childhood. This suggests a genetic link. It's likely that the interaction between genes and environment aid in the development of the disease.

Disconnection From Body Signals

Anyone who's ever dealt with hunger pains has likely wondered how a person with anorexia can go so long without eating. Sensitivity to body signals such as a growling stomach or a hunger-induced stomach ache is called interoceptive awareness. People with anorexia may have reduced interoceptive awareness. This not only reduces their sensitivity to hunger cues. It also means they get less satisfaction from filling an empty stomach than people with strong interoceptive awareness might.

Research has found that people with anorexia also have difficulty identifying emotions. It could be that lacking interoceptive awareness also plays a role in this phenomenon.

Reward Insensitivity

You might not realize it, but eating is an inherently rewarding activity. Satisfying hunger feels good both physically and emotionally, so doctors have long wondered how anorexics can ignore the rewards typically associated with eating. People with anorexia are remarkably insensitive to rewards, and are able to deny themselves many of life's pleasures, seemingly without suffering. Research has found that this observation isn't mere anecdote; those struggling with anorexia show an increased ability to delay rewards — such as money — in behavioral studies.

Brain imaging studies have shown that anorexics are both insensitive to rewards and highly sensitive to punishment. In other words, they're obsessed with the consequences of their actions. While most people would be absorbed in the immediate pain associated with being hungry, anorexics fixate on the consequences of eating — gaining weight. There's an increasing volume of evidence suggesting that this phenomenon may be due to an under-active limbic system coupled with overactive executive functioning.


It should come as no surprise that anorexia is associated with anxiety. People with the disorder tend to obsess over their weight and how they appear to others, and they frequently set impossibly high standards for themselves. People with the disorder are particularly fixated on avoiding harm. This might seem strange, given how harmful avoiding food can be. But anorexics view gaining weight as a source of harm, not starving themselves. It makes sense, then, that they'd have the fortitude to continually deprive themselves of food as a response to anxiety.

Biochemical mechanisms help to explain the anxiety of anorexics. One study found that increased dopamine release might be a source of anxiety for anorexics, rather than a source of pleasure, as it is for most people. Consequently, the reward of eating may actually increase an anorexic's anxiety.

No single factor can fully explain every case of anorexia, and different anorexics experience different risk factors that lead them to develop the disease. But by understanding anorexia's central causes, clinicians can gain insight into how to treat this debilitating disorder.


Eating disorder statistics. (n.d.). Retrieved from…

Eating disorder statistics. (n.d.). Retrieved from

International study provides new genetic clue to anorexia. (2013, September 11). Retrieved from

Kaye, W. H., MD. (2014, May 6). Eating disorders: Understanding anorexia nervosa. Retrieved from…

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