Understanding the Neuroscience of Anorexia and Anxiety

Have you ever felt “hangry?” You know — that irritable, cranky, sometimes desperate feeling that comes up when you’ve gone too long without eating? That edgy feeling of “hanger” happens when our blood sugar levels drop too low and trigger hormones that function to rebalance blood sugar. These hormones include adrenaline and stress hormones like cortisol, which are associated with aggression and a decrease in impulse control. Hence the rage and fury of a person who is just too darn hungry!

It’s interesting to think about individuals with anorexia because it often seems that they are less sensitive to hunger.

In fact, folks with anorexia will often share that they feel best when they’re empty or hungry.  Studies of the brain of people with anorexia suggest that there is a physiological reason why a sense of well-being is associated with restricted eating for folks with AN.  

Before important research on anorexia uncovered the biological basis for the condition, medical professionals believed that people with anorexia were vain and willful individuals who simply needed to choose to get better. Early on, Walter Kaye, a leading researcher in the field of eating disorders, disagreed and hypothesized that biological influences were at play. He believed that identifying these underlying factors could lead to more effective intervention and treatment.  He was absolutely right. With years of research and deeper understanding of the neurological processes behind anorexia, we’ve been able to reduce the stigma and blame that previously had been associated with the disorder. 

Supporting this idea, “Heather” shared her story with The Atlantic in an article about the challenges of treating anorexia in adults. She recalled the first time that treatment providers explained the neuroscience of anorexia and anxiety to her. “I realized I wasn’t completely crazy,” she shared. “It was a huge relief. It is real, and I’m not making it up…” By recognizing that anorexia is not about vanity or will but instead, driven by biological factors, it is much easier to address the eating disorder with compassion and understanding.

Let’s take a look at some of Kaye’s research findings as they relate to the neuroscience of anorexia and anxiety.

Motivation and Reward

Kaye wrote, “One reason that people with anorexia are able to starve themselves is that, when they get hungry, the parts of the brain that should be driving reward and motivation just aren’t getting activated.” Further proving this point, one study looked at the brains of women who recently recovered from anorexia. Their brains responded less intensely to sugar water than their healthy counterparts. Even when they were hungry, this group found sweets less rewarding. For instance, that feeling of “yum!” when you take a bite of chocolate cake doesn’t happen in the anorexic brain. The reward area of the brain remains quiet, while the fear response is in overdrive. Through fMRI research, Kaye discovered that, unlike most people, “people with anorexia are generally more sensitive to punishment (the removal of something pleasant) than reward.”

Cerebrospinal Fluid

Women with a vulnerability to anorexia had a high level of serotonin in their cerebrospinal fluid. Too little of the “feel-good neurotransmitter” is linked to depression, while too much is linked to chronic anxiety and irritability. It makes sense, then, that 75 percent of individuals diagnosed with anorexia also suffer from anxiety, social anxiety, or obsessive-compulsive disorder (OCD). Further connecting the two mental health conditions, Kaye believes that too much serotonin even makes certain individuals more susceptible to anorexia.

Serotonin and Tryptophan

Tryptophan is needed for the synthesis of serotonin. When you consume less food, your levels of this amino acid decrease, which also reduces your serotonin levels. In individuals with anorexia, starvation reduces the levels of both tryptophan and serotonin in the brain, which then reduces anxiety. This connection partially explains why people with anorexia don’t experience being “hangry.” 

The problem is however, that the brain retaliates. Over time, starvation leads to the creation of more serotonin receptors in an effort to “wring out” more serotonin. This increased sensitivity to serotonin, then, leads to increased irritability and anxiety. When the individual eats, there is a surge of serotonin that causes them to feel anger, panic, and instability. This negative feedback loop locks into place and eating becomes associated with anxiety and discomfort.

Fortunately, a better understanding of the neurological mechanisms behind anorexia has shaped treatment and has made recovery for individuals with anorexia more possible.

Additionally, social supports for these individuals are able to access much more compassion and understanding when they learn that anorexia is a biologically-based condition and that many of the behaviors are driven by brain chemistry gone awry.  

Do you know someone who is suffering from anorexia? Reach out to us at Columbus Park to learn more about our evidence-based approach to treatment.