The neurology behind eating disorders

Starvation and Neurology

Neurological Background of Eating DisorderS

Mental illnesses can never be separated from our nervous system. Depression is caused by a metabolic disorder in the brain, post-traumatic stress disorder (PTSD) is related to the nervous system's ability to store trauma in the body. Unfortunately, mental illnesses are still far too often considered separately from neurological backgrounds. Restrictive eating disorders still have the reputation of being triggered exclusively by the wrong role models - a myth that most sufferers probably contradict. ED Ouelette, a coach in the field of eating disorders, is convinced: "If we were to rename the disease anorexia, we would call it a malfunction of the reward center in the brain."

Evolutionarily, we humans are designed in such a way that our reward center in the brain is activated when we eat. This function was particularly important in the early stages of our species' development in order to protect it from starvation. In people with restrictive eating disorders, however, the exact opposite can be observed: Here, the fear center lights up, while the reward center is stimulated by starvation.

But humans are not the only creatures to develop eating disorders. In a 2003 paper, researcher Shawn Guisinger sheds light on the so-called adapted to famine hypothesis. This adaptation, which explains how different people respond to famine, covers several areas. The urge to move, which people with eating disorders often feel, was originally an important mechanism for finding food. If a herd lived in an environment that did not provide enough food, it had to move on, no matter how exhausted and emaciated it was. Evolution found a way to suppress weakness and powerlessness and increase the urge to move to ensure survival.

The core symptomatology of restrictive eating disorders also includes three different adaptations that are specifically relevant to surviving famines in the past: Ignoring food, hyperactivity, and hunger denial, including a distorted body image. From an evolutionary perspective, food denial served two important functions: First, it allowed one's offspring to eat what little food was available, and second, it allowed the herd to focus on finding a more suitable feeding site overall, where more food would be available in the long run.

Interestingly, members of a herd, group, or family have always differed in their responses to starvation: A smaller portion of the group responds with behaviors we know from people with restrictive eating disorders in order to ensure the survival of the rest of the group or family. Simply put, each group has a few people who would die for the survival of the others - which explains why some family members develop eating disorders and others do not. The development of these symptoms is due to malnutrition or weight loss.

It doesn't matter if this is intentional (dieting, fasting) or caused by illness or stress. However, this insight is extremely important for the treatment of eating disorders, because it reverses the roles of cause and effect: For a long time, it was believed that eating disorders led to dieting, whereas the opposite is often true: Dieting leads to eating disorders. Experiments from the 1980s and 1990s show that pigs and rats that were put on a diet developed severe eating disorders over time. This was not true of all the animals, but some of the study groups seemed predisposed to eating disorders. The affected animals refused to eat enough food and began to exercise excessively. The malnourished rats used their treadmills day and night, even though they consumed far too little energy.

The pigs developed a behavior that we know from humans today: They began to eat excessive amounts of the low-nutrient straw, possibly to escape feelings of hunger. This is similar to the large amounts of vegetables or salad that many people with restrictive eating disorders eat. This volumetric eating is intended to make hunger more bearable without consuming calories. However, while humans can calculate and count calories, for pigs it seems to have been more of a primal instinct to eat low-calorie food in order to leave more nutritious food for other animals in the herd.

People with depression are particularly prone to developing restrictive eating disorders. One reason for this may be that people with depression are more likely to fall into an energy deficit due to symptomatic loss of appetite. In addition, depression, like eating disorders, is a very self-destructive disease. In the case of depression, virtually any means is good to inflict more damage on oneself, which in some people manifests in the development of an eating disorder, which can also be a form of emotional regulation.