Does This Outfit Make My Schema Look Fat?

I have done a lot of driving (around 600-700 miles a week) for my job this summer, and I have spent some time contemplating how people’s cars become an extension of themselves on the road. That inspired me to read up on proprioception and cognitive body maps (yes, I can be a NERD!) and I have found some interesting hypotheses about how the neurology behind our perceptions of ourselves can lead to eating disorders. (This post turned out to be a little bit long, I am easily wrapped up and carried away by science topics, but trust, me it’s cool stuff!).

One of the core concepts is that of the body schema, and how that differs from body image. In a nutshell, body image is how we perceive ourselves. Not the literal reflection in the mirror, but our subjective reaction to it and feelings about it. This does not necessarily correlate to physical reality, and includes many psychological and cultural factors. Someone that weighs X in a given culture might view themselves much more or less positively than a person of the same proportions in another society. Same physical image, different cognitive body image.

Body schema, however, is much different. It is a neurological map based on actual physiology, and results from our networks of sensory receptors that keep our brains informed about the location and activity of all of our bodily bits and pieces. It incorporates the five classic senses everyone learned in kindergarten, in addition to balance (via the vestibular system) and our awareness of the space immediately surrounding our bodies (aka “peripersonal space”).

So, how do these concepts interact, and how are they distinctive in people with eating disorders? Some researchers have suggested that diets spiral into eating disorders when our two types of body maps become mismatched as a result of weight loss. Basically, body image is based on a library of experiences, emotions, and other psychological factors that are stored as steadfast beliefs in the areas of our brains responsible for memory. As anyone who has battled an ED knows, it is very, very hard to alter thought patterns that you have held, year in and year out, for decades. Sometimes it seems damn near impossible. That disordered voice becomes the default reaction to almost any situation involving food, body size, etc.

In contrast, your schema—a purely physical phenomenon based on sensory input—will automatically adjust itself as you lose weight. This allows you to maneuver your 'new' body without regressing back to bumbling around like and adolescent klutz (awkwardness in adolescence is also thought to be a proprioreception issue, caused by sudden growth spurts).

Thus, when we lose weight, our body schema and body image can get out of sync. Your body gets smaller, but psychologically you fail to perceive the change. This is one reason it is common to get a shock when you pull on clothing you have not worn in a while, and find that it doesn’t fit the way you expected it to. This can happen in different contexts: finding your summer clothes are unexpectedly snug after adding poundage over the winter, or being surprised at how loose your jeans have become after shedding a little weight. You might have been aware that your numbers (pounds, etc) have changed, but it is still surprising to be confronted with physical evidence that contradicts the way you are accustomed to viewing your size/space requirements.

Studies have suggested that body schemas seem to be formed by circuits in the right parietal lobe of the brain (yellow arrow in image). Interestingly, fMRI scans of recovering anorexics have shown much more activity in the left hemisphere of the brain when patients are at low weights, with a shift towards more activity in the right hemisphere—especially in the parietal region—as weight is restored. This could explain why ED recovery is inhibited by irrational thoughts and anxiety unless someone is able to push through and restore weight.

So, the take-home message from all this data: Eating disorders can be triggered by a lag in aligning our psychological perception of our bodies with physical changes, and building physical health can be a tool in restoring healthy thought patterns.


A couple more thought provoking points of interest related to asynchronized image/schema and EDs:
~ Testosterone has a profound influence on development of the right parietal lobe. This explains the fact that—on average—men outperform women in tests of spatial abilities. Could it also be a factor in explaining why women are more likely to let a diet spiral into an ED, do females just have a harder time with syncing their body image to their body schema? Statisically, females are more likely to have neurological imbalances that affect the right parietal. Some scientists have suggested this as an explanation for the fact that EDs strike females more frequently than males, although the issue of culture and societal pressures can’t be overlooked when examining the gender issue.

~In a study on tactile perception (explore a figure with your fingers only, no peeking, and then draw it), anorexics performed miserably compared to other people, despite having higher average IQs.

~It is thought that our body image tends to become solidified (via specific neural circuits) in adolescence, around the time of puberty. This could explain why this is a common age for developing an ED. Of course, someone can fall into an ED at any age, but the teen years are thought to be especially high-risk.

~All of this evidence for neurological factors, which are based on the physiology of the brain, give support for the idea that EDs and related psychological conditions are heritable, aka that they “run in families.” I have EDs and alcoholism on both sides of my family, so I’ve always believed there is at least some genetic component, this supports that theory.


The bulleted points are hypotheses, ideas for things that could contribute to EDs but certainly don’t explain everything. Cultural factors can't be overlooked, but there is more and more evidence accumulating to show how culture can act as a trigger on specific biological phenomena that leads to disordered thoughts and behavior. See this article for a terrific overview of more information on current research about the science behind eating disorders.


(Image credit)