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The Neuroscience Behind Anorexia

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Although it may start that way for some, anorexia is not “a diet gone too far.” No consciously chosen diet would take you to the point of organ failure. In reality, an eating disorder is so much more than that — it’s your brain detecting a stressor (real or perceived) and focusing on escaping from that stressor. In the process, it deprioritizes all non-essential biological mechanisms to focus on escape, including slowing digestion (reducing appetite in the process) so it can increase absorption of sugars from the digestive tract and give your muscles energy to run away.

In neuroscience, they say, “those that wire together fire together,” so for those with a genetic predisposition with persistent stress, the brain learns if you feel stressed you eat less. Eating less becomes wired with the stress response and so if you eat more, you become stressed. Eating less then makes your brain more anxious as the brain enters “famine mode” and the threat becomes hunger. The lack of food increases your anxiety and decreases your mood (you need food to feel joy) making you depressed, and you become stressed and anxious by the very essential thing keeping you alive, food.

Food becomes the stressor. It isn’t a diet gone too far, it’s not a choice, it’s not you not liking food, instead it’s your brain wiring stress and food together and evoking anxiety around eating and food. However, with the right treatment for the anxiety, the right re-nutrition to help nourish the brain and leave famine mode, you can re-wire your brain, find peace, and learn to get palatable joy from food again. Anorexia is not a choice or identity, but a temporary brain illness, completely and sustainably recoverable with the right treatment.

Anorexia Is Not a Choice, but Recovery Can Be

Although getting anorexia is not a choice, recovery can be. Our brains are neuroplastic. They are forever wiring and rewiring so that with decreased threat, lots of nutritious food to help improve mood and leave famine mode, sleep and sustained practice, we can rewire the stimuli and response mechanism and relearn how to remove the “food is threat” response. We have to face our food fears and become desensitized to them. However, the longer the stress and behavior (eating less) become wired together, the harder they are to unwire. This is why early intervention is so critical.

Those with a larger amygdala, the emotional reasoning part of the brain, are more susceptible to anxiety and thus to eating disorders. The emotional part of the brain is affected by oestrogen (one of the reasons women are more susceptible to eating disorders than men) as oestrogen plays a role in serotonin (the happiness chemical) levels and mental well-being.

Over-exercising can reduce oestrogen, which could be part of why anorexia is very prominent in athletes (as part of athletes triad). Too high (intense happiness) and too low serotonin (depression) levels and fluctuations in serotonin increase anxiety and thus increase the chance of someone developing an eating disorder. Healthy eating includes foods high in tryptophan (the serotonin precursor) which is why “orthorexia” or “extreme healthy eating” can lead to improved mood — but then anxiety if in excess.

When I talk about anxiety, I don’t mean that some people are weaker than others. Not at all. In fact, one theory states that people with a predisposition to anxiety are more evolved than those who are not. This is because of the flight or fight response. According to Charles Darwin and his “Origin of Species,” the “evolutionary aim” of a species is to prevent species extinction. To do this, a species must survive against natural disasters, predators, extreme environments, and outcompete other members of the species for shelter, space, food, and a compatible mate and produce fertile offspring. The “flight or fight” mechanism helps organisms to survive. This is a biological mechanism from our evolutionary ancestors which helps us to detect a threat to survival and run, defend or hide from a threat. This occurs via increasing adrenaline and cortisol which effects the body in the following ways: it dilates pupils, increases our heart rate, decreases digestion (and appetite so you feel fuller) and reproduction (including oestrogen and testosterone production) and moves the blood to the muscles to combine with glucose from our diet in respiration and give us the energy to run away from the predator.

Therefore, those caveman ancestors with a higher predisposition for anxiety — “the premeditation or anticipation of stressor” — were more likely to detect the predator first and survive based upon the principles of “survival of the fittest.” Whether environmental (from their lives) or from within (for example, putting yourself under a lot of pressure to succeed), this anxiety is not weakness, but a biological advantage. It actually can be the sign of a more evolved brain, of greater intelligence, of being more likely to recognize a threat and of having a greater chance of evolutionary survival. But, it also puts you at higher risk of eating disorders and other mental illnesses linked to anxiety.

How we respond to stress depends on our genetics. Whether we get a decreased or increased appetite in response to stress depends upon our genetics. This is why stress plays a role in anorexia and in over-eating. For those with a genetic predisposition to anorexia, stress makes you full.

People who are more likely to get anxiety include those with stressful upbringings or jobs, those under a lot of pressure from others or themselves (including “Type A personality” highly ambitious people) or financial pressure, those with a lot of time with technology, limited sleep and limited access to outdoor spaces and nature in cities, those alone (as relationships, family, friends, and community increase oxytocin which reduces anxiety), women (due to the role of oestrogen on anxiety levels), “emotional people” whose genetics result in larger amygdala’s (which also evokes more creativity, greater memory and thus intelligence, greater empathy, and compassion) and those with much indecision or uncertainty in their lives (one of the reasons eating disorder levels rose during the pandemic). In cognitive behavioral therapy, the idea is that a thought (including an anxious thought), leads to a feeling that leads to a behavior. Thought> feeling>behavior.

When it comes to anxiety and eating disorders, there are two main focal points:

  • Frontal Lobe: Controlling emotions, impulse control, judgment, behavior, memory, thought processing.
  • Limbic System (including amygdala and hippocampus): Emotions and stress (real or perceived), memory, and thought processing.

Anxiety, via the “flight or fight reflex,” can steal your appetite and stop you feeling hungry, but also gives your muscles fuel, so you feel hyper. With a reduced appetite, you naturally eat less. With increased energy you do more. Over time, your brain wires stimulus and response together, so if you eat less when you’re chronically worried, if you eat more, you get stressed. Food becomes the stressor. You don’t “not like” food. You don’t “choose to not eat” — but your brain makes eating stressful and gives you anxious energy, reducing sleep and increasing activity. This is why anorexia is so hard to fight and is why lapses and relapses are common in periods of stress or anxiety, such as life changes or if the threat or stressor is not removed. If the stressors from before are not changed, relapse risk is high. To prevent relapse, patients must mine the thought and feelings and environments that trigger their behavior and try and avoid them or develop coping mechanisms to them. They must learn ways to move their brains from “flight and fight” to “rest and digest” and feel calm and hunger and at ease with food again.

Brain re-wiring takes practice and reinforcement as new neural pathways are weaker, less strong than old ones (which is why habits are so hard to get rid of). Recovery takes incentives for practice (support, goals, reasons to recover, knowledge of repercussions if you don’t recover), and sustained practice and maintenance of new brain pathways. It means facing your fear foods (often in anorexia, high calorie, fat, or carbohydrate foods associated with weight gain, another anxiety-producing fear in anorexia). Sleep, good nutrition, and the removal of stressor all help reinforce memory (in the brain hippocampus and frontal lobe) and neuroplasticity, reducing anxiety. They also stimulate BDGF (brain-derived growth factor) which plays a role in the formation of new neural pathways. Relapse prevention is about maintaining a constant external environment so you can maintain a constant internal environment. It is doing what you can to mitigate changes and remain constant and reinforce those new brain pathways.

Finding Order in Disorder With an Eating Disorder

Initially in anorexia, it is not about food. It is a maladaptive coping mechanism for dealing with thoughts, feelings, and environments. Our brains use control over food as a way of “calming the chaos” in our lives. To find order in the disorder with an eating disorder. You can’t “choose” this, it’s a nervous system response out of voluntary control. To fight it, you must “re-wire” your brain, which is incredibly difficult, but I, as living evidence of this, can confirm it’s not impossible.

In recovery, I have learned tools to manage my “old brain” and how it responds to stimulus and think more rationally and logically. In between the emotional and logical brain is the wise brain. I have neuroplastically developed my “new brain” neocortex and, with CBT and mindfulness, have learned to interrupt the mechanism that links feelings and unhelpful behaviors and enter this “rest and digest” brain mode. I am consciously aware of how my emotions (how I feel) impact and skew my decisions, interpretations of life events, how I respond to situations with my behavior, and have learned to always question how I am feeling and ensure I am basing decisions on evidence and logic, rather than solely emotion.

I have learned that when tired, with too high or low blood sugar, too much or too little social stimuli, hungry, ill, and on my period, I am less able to control my emotions and so use healthy coping mechanisms like sleep, yoga, rest, classical and jazz music, hot baths, walks in nature, and socializing to disrupt anxious thoughts, stop unhealthy behaviors, and switch my brain from the “sympathetic” stress response to the “parasympathetic” relaxation response. I know that deep breathing and yoga is a great quick way of switching one “flight and fight” brain mechanism to the next “rest and digest.” I know my triggers and know how to disarm them! With this I have hijacked the mechanisms that link the food and feelings and, as long as I stick to what works for me (which with food, is three relaxed meals and three snacks and activity for leisure), I can live a full and wonderful life. I now get no angst around and can happily confess I love food. I am a rabid flavor machine, using cooking as creative expression, trying it all and using meals (my famous potato pie especially) as a way of bringing together my wonderful “good eggs,” the people I care about. Unlike when I was anorexic, I now eat and enjoy what I cook. I am at peace with food again and if a hideously average person like me can do this, so can you. Sustained health maintained recovery from anorexia and other eating disorders is possible for everyone.

If I can do it, so can you.

See more from Laura on her site

Getty image by digicomphoto

Originally published: April 6, 2022
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