Eating Disorders and the Brain
Eating disorders are biologically based brain illnesses influenced by environmental and psychological factors. Environmental risk factors for developing an eating disorder include weight and appearance pressures, media messaging, and weight bullying. Biological factors include dieting/food exposure, genetics, neurochemistry, neurobiology, and hormones (notably estrogen). Psychological factors include stress, life transitions, identity, trauma, anxiety, depression, and substance use.
While risk factors predispose certain individuals to eating disorders, precipitating factors such as significantly altering how one eats or stressful life events make may an individual more likely to develop and eating disorder. Once an eating disorder is present, maintenance factors take over. These factors that maintain an eating disorder include biological changes that occur as a result of disordered eating and psychological factors that are connected to the eating disorder behaviors that then turn and reinforce a person’s repetitive, disordered behaviors.
What makes certain individuals vulnerable to developing an eating disorder?
Eating behavior is mediated by a large network of interacting neural circuits that include numerous areas of the brain, including the prefrontal cortex, anterior cingulate, insula, and the amygdala. We know that our eating behavior is determined by several signals that come into our brain through our mouth or through our gut. The experience of eating (Does this food taste good? Am I hungry? Where am I?) then propels us to keep eating, to stop eating, or somewhere in between. For example, if you are hungry and the food you are eating tastes good, you most likely will decide to keep eating. If you are eating loud food but are in a quiet meeting, you may choose to stop eating and eat your food following the meeting as to not disturb anyone.
In addition to this understanding, our gut also influences our eating experience. While research on the gut microbiome is still emerging, we know this is an essential component of eating that affects our eating behaviors. For example, if we feel ill upon eating certain foods, we may alter our eating behaviors in order to address this and prevent feeling sick.
Two experiences of eating
There are two parts of eating, “liking” and “wanting,” that inform our understanding of why people keep eating even when they are not satisfied and how the reward of eating may be exaggerated or scant. The wanting part of the eating experience is our appetitive system that motivates us to go get food. It says, “I’m hungry, go get food.” This is involved in the anticipatory reward of eating. If we are hungry and know we are going to get food soon, there is likely a reward associated with the knowledge we will be eating soon. As we understand now, we believe dopamine is involved with this wanting and drives us to seek out food.
The liking centers come in after wanting—they are what happens after we get the food. The “liking” is a response to eating. This liking reaction is reinforcing if we like something and not if we don’t. For example, if we are hungry and eat a meal we enjoy, our liking reaction reinforces that we enjoy that type of food. However, for those that struggle with eating disorders, they may “want” something but once they get it, they may not find it enjoyable.