Listen to the beat of your heart: A new explanation for distorted body image in EDs
I’ve always had a tough time trying to explain my distorted body image to others. How could I perceive my weight as normal or even grossly overweight, when the scale and my clothes clearly dictated something different? I’ve always struggled with body misperception. Granted, I’m no twig and never have been, but I’ve never been able to perceive my body accurately. Ever. As long as I can remember, my body felt huge. I still have no objective idea of my own size. I know (in general) what size I wear and roughly what this means, but I’m constantly filled with this nagging doubt and paranoia about what size I actually am. I feel huge. Accepting that this isn’t reality and, perhaps more significantly, that I have no way to change these feelings but I can learn to live with them, let them pass, and not let them define my self-concept (that is, regardless of what size I may or may not be, that doesn’t affect my ability to be a good writer, cyclist, daughter, girlfriend, cat mom, etc) has been the most helpful.
It still doesn’t answer the nagging question of why I felt like this in the first place. Cultural factors are an obvious place to start–how could someone (especially a female someone) not feel too large in an ocean of digitally altered advertisements and unattainably slim models? Certainly these might be a factor, but I don’t believe it’s the only factor. It’s not just that I, and many other people with EDs, feel “fat”; it’s that we have no real concept of our own size. It’s as if the brain can’t perceive the size of the body.
Researchers have begun looking at a factor known as interoception in the etiology of eating disorders. Interoception is, simply put, our ability to perceive the internal state of our bodies, everything from hunger and thirst to warmth and exhaustion to how we’re feeling. One of the very first questionnaires developed to measure ED symptoms (the Eating Disorders Inventory) has a subscale that measures interoception. People with eating disorders have, on average, lower levels of interoception than healthy controls. When researchers were testing the validity of a newer version of the EDI (the EDI-3), they found that interoceptive deficits was actually the strongest predictor of ED psychopathology across all different ED diagnoses (Clausen et al., 2011). A study in the International Journal of Women’s Health found that higher interoception seemed to be a protective factor against the development of disordered eating in adolescent girls (Gustafsson et al., 2010).
A new study by neuroscientists Vivien Ainley and Manos Tsakiris of Royal Holloway, University of London, published this week in PLoS ONE, has linked impaired interoception with self-objectification. We’re not born with a pre-formed body image. Babies have neither a body image nor a sense of self. They exist in a confusing sea of sights and sounds, with no real sense that they can navigate this world or make things happen. As a caregiver response to a baby’s cries for food, burping, or a diaper change, the baby begins to develop an awareness of self, that they can make people respond. Psychologists call this a sense of agency. The growing child begins to see him- or herself as the narrator in their own life story. They are the subject of this particular plot. Everyone else around them are “objects,” and are viewed as separate from the self.
Thinking of yourself from another’s perspective is called “self-objectification.” You’re treating yourself as if you were an object in your own life. Researchers asked a group of 204 healthy undergraduate women a variety of questions about body shame, eating disorder symptoms, how much they tried to control their diets, and self-objectification. Those women that most frequently thought of themselves from other people’s perspectives had the most eating disorder symptoms (Noll & Fredrickson, 1998). Typically, these high rates of self-objectification in people with both disordered eating and eating disorders has been linked to cultural factors like models, advertising, and over-sexualization (Fredrickson & Roberts, 1997; Fredrickson, Roberts, Noll, Quinn, & Twenge, 1998; Calogero, Davis, & Thompson, 2005). But Ainley and Tsakiris have a different hypothesis- that women with EDs think of themselves as objects because they lack a good internal sense of self due to their impaired interoception.
To formally measure a person’s interoceptive skills, researchers use what’s known as the heartbeat test. Study participants attempt to count how many time their heart beats in a minute without taking their pulse. Researchers then simultaneously measure their pulse electronically. Good interoceptive skills, researchers hypothesized, meant that a person is better able to sense the subtle lub-dub as their heart pumps blood and will report a pulse that is closer to the actual recorded value. When researchers compared the results of 17 people on the heartbeat test to other measures of interoception, they found that, indeed, better interoceptive abilities meant the estimated heartbeat was significantly closer to the measured value (Critchley et al., 2004).
Ainley and Tsakiris administered the heartbeat test to 50 female undergraduates (ages 19-26), along with questionnaires assessing self-objectification, body consciousness and self-consciousness. The researchers found that interoceptive awareness (as measured by the heartbeat test), and public and private body consciousness (which measures your awareness of internal and external body states) explained about 31% of the variance of self-objectification. The results are plotted below; caption from the study.
The authors conclude that
Our results suggest that low interoceptive awareness may be a cause rather than an outcome of high self-objectification if women for whom internal stimuli are experienced, for innate or developmental reasons, as less salient, tend in consequence to direct their attention to their bodies from a third-person perspective…The results of our study, show that high self-objectification is predicted by low interoceptive awareness, implying that women who self-objectify are those who are relatively unaware of the interoceptive cues which are related to their emotions and who may also therefore experience emotion less intensely . Such women may be vulnerable to clinical conditions associated with poor interoceptive awareness, such as anorexia, alexithymia and somatoform disorders. For example, poor emotional awareness, as measured by the Toronto Alexithymia Scale , has been shown to mediate between self-objectification and eating disorders, .
It is an interesting conclusion, though it’s by no means decisive. It’s also important to remember that other studies have found abnormally high levels of interoception in people with anorexia. Still, this study helps to link some of the most baffling features of eating disorders: how can people have such a mismatch between how their body feels and how it actually appears? How can someone not notice that they’re hungry or sad or whatever? How can they be so blithely unaware of their own illness?