I’ve seen periodic position statements on how thin models/media/thin privilege/celebrity culture don’t cause eating disorders in our kids. But instead of causes, I would like to look at contributions in this blog post.
Of all the kids in the world, some have a predisposition to get motion sickness. And of that subsection, many of them will have felt nauseous in a school bus or on field trip and they ended up throwing up. But not all of those kids who threw up will subsequently develop a phobia of throwing up (emetophobia).
The prevalence of motion sickness in our populations is about 28%. The prevalence of motion sickness is highest in those with schizophrenia (30%) and lowest in rowers (0%)—although I suspect that those with motion sickness would not be keen to be in a tippy boat travelling backwards at high speed on the water in the first place, making rowing a self-selected pastime. 1
The prevalence of phobias (all inclusive) is estimated at 6.2% in the US. 2 The prevalence of emetophobia is estimated between approximately 2 to 7% (lower range for men and higher range for women). 3
When someone has a predisposition to feel sick when in motion or to create an energy deficit in the body (the underpinning of an eating disorder), then there is an underlying genetic component involved in its initial activation. There are also subsequent sociocultural influences and life experiences that may reinforce that initial activation to twin it with anxiety or, conversely, ease its expression back to a fully latent state (remission).
Of all the kids in the world, a subsection will have the predisposition to create energy deficits in the body. Unlike the kids predisposed to motion sickness, a far greater number of those with a drive to create energy deficits in the body subsequently develop full-blown eating disorders.
Not all examples of emetophobia will originate from a predisposition to motion sickness of course. But even if we allow for the fact that emetophobia has numerous origins, why is the conversion from initial activation to full-blown condition higher for those with eating disorders than for emetophobia?
A maximum of 7% of our population suffers from emetophobia, yet a theoretical potential of at least 28% of the population could develop the condition because they have a predisposition to be sick when in motion. It takes more than just being sick while in motion to develop emetophobia and the same is true of restricting food intake and developing an eating disorder. But we are clearly creating an environment that is converting, or reinforcing, the behaviors in more individuals with the predisposition to develop an eating disorder than what we are currently seeing with emetophobia. Let’s take a look at the numbers:
While you may be used to seeing prevalence rates for distinct Diagnostic and Statistical Manual for Mental Disorders (DSM) eating disorder categories that suggest lifetime rates of between 0.3% to 2%, as an entire spectrum disorder that can impact quality and length of life, the much broader prevalence of approximately 25% is more accurate.
Problematically, almost all clinical trials identifying the prevalence of restrictive eating disorders use the narrow, and largely unrepresentative, symptom checklists found in the DSM for identifying those with restrictive eating disorders. When Dr. Daniel Le Grange and his colleagues reviewed and analyzed community-based surveys to uncover eating disorder prevalence, they offered the following conclusions:
“Although the lifetime prevalence estimates of eating disorders from population-based studies of adults are relatively low (0.5%–1.0% for anorexia nervosa [AN] and 0.5%–3.0% for bulimia nervosa [BN])…community studies that used dimensional measures in youths have also yielded far greater prevalences of disordered eating behaviors (ie, 14%–22%) than those found in studies that applied strict DSM-IV diagnostic criteria.” 4
Hence, it is much more representative of actual lived experiences to indicate a quarter to a third of all people who restrict food intake (involuntarily or voluntarily) will end up with an active eating disorder. 5, 6
It’s possible that the genetic drive to create energy deficits in the body works something like motion sickness. But whereas only 2-7% have emetophobia in our population (and a subsection of those will have had the condition activated because they were prone to motion sickness), some 14-33% of our population have an active eating disorder from a theoretical potential of 25-33% of the population that perhaps have a drive to create energy deficits in the body.
I’ve mentioned Dr. Shan Guisinger’s work in other blog posts and her theory that this drive to create energy deficits in the body might have had adaptive value for nomadic foraging humans. 7 Whatever the adaptive value might be for this predisposition to exist, we can generate higher rates and more severe expressions of the condition in our populations by creating sociocultural environments that exacerbate the conversion from activation to debilitating chronic condition.
I could likely increase the rate and severity of emetophobia in our population. It might look like this:
Imagine if every day I could expose you and especially our kids to several thousand media exposures (online, TV, magazine, newspaper...) that told you riding around in vehicles that travel above 30 km/h with more than three people in the vehicle, will harm your health.
Some articles let you know that there's new data to confirm that even two people in a vehicle going 40 km/h has been linked to high blood pressure and diabetes. Others point out that motion sickness should be recognized as the body’s natural protection of the dangers of riding in high-occupancy vehicles (HOVs). Studies show that riding public transit suppresses immune function, and generates higher rates of cardiac arrest, anaphylaxis, and injury (where of course the data don’t sift out confounders).
Still others point out that those who ride around in high-speed HOVs are being irresponsible slobs who are ignoring all the health warnings. Your government is now planning to implement taxes to curb people’s use of HOVs to deal with the epidemic of health problems associated with their use.
At your school, they implement a “healthy riding” educational outreach blitz. The kids are given an in-class assignment to write down how many times they’ve been a passenger in a car, bus, plane or train where there were more than two people. Those who have more than two such events per week are given a letter to take home to the parents explaining that their kid is at risk for immunosuppression, heart attack, diabetes, high blood pressure and early death. The letter also conveniently explains how the parents can help their kid make better travel decisions to lower her health risks over time.
This entire scenario plays out for real everyday across our media and our schools for ‘healthy’ food, exercise and obesity ‘prevention’, and it has exactly the same level of absurd connection to actual health outcomes as high-speed HOVs would have. While the drive to create an energy deficit in the body may be as baked into the genetic cake for some as is motion sickness for others, we as an entire society own how much gasoline we decide to fire hose onto that tinderbox of anxiety.
If we really want to lower the incidence of eating disorders in our societies, then we have to start getting much more accurate about how food and exercise have absolutely no link to obesity onset or prevalence rates (see this and this) and that obesity has no causative role in morbidity and mortality outcomes for anyone, ever, at all. But there is a causative role eating disorders play in generating mortality rates 12 times higher for ages 15-24 than all other causes of death combined (that includes car accidents). 8 If obesity really were the killer we keep telling our kids it is, and if it were at epidemic levels caused by sodas, fast food and lack of exercise, then we’d see it all in the cold, hard, irrefutable mortality rates and we’d sure as heck have some solid causative data at this point given how many billions have been poured into to obesity research in the past twenty years too.
All we have to show for all that gasoline poured onto the fire is pretty awesome conversion rates from genetic predisposition to full blown eating disorder. Yay us.
1. Sharma, Krishan. "Prevalence and correlates of susceptibility to motion sickness." Acta geneticae medicae et gemellologiae: twin research 46.02 (1997): 105-121.
2. Boyd, J. H., et al. "Phobia: prevalence and risk factors." Social psychiatry and psychiatric epidemiology 25.6 (1990): 314-323.
3. Hunter, Paulette V., and Martin M. Antony. "Cognitive-behavioral treatment of emetophobia: The role of interoceptive exposure." Cognitive and Behavioral Practice 16.1 (2009): 84-91.
4. Swanson, Sonja A., Scott J. Crow, Daniel Le Grange, Joel Swendsen, and Kathleen R. Merikangas. “Prevalence and correlates of eating disorders in adolescents: Results from the national comorbidity survey replication adolescent supplement.” Archives of General Psychiatry 68, no. 7 (2011): 714-723.
5. Jones, Jennifer M., Susan Bennett, Marion P. Olmsted, Margaret L. Lawson, and Gary Rodin. “Disordered eating attitudes and behaviours in teenaged girls: a school-based study.” Canadian Medical Association Journal 165, no. 5 (2001): 547-552.
6. Shisslak, Catherine M., Marjorie Crago, and Linda S. Estes. “The spectrum of eating disturbances.” International Journal of Eating Disorders 18, no. 3 (1995): 209-219.
7. Guisinger, Shan. "Adapted to flee famine: Adding an evolutionary perspective on anorexia nervosa." Psychological Review 110, no. 4 (2003): 745.
8. Sullivan, Patrick F. “Mortality in anorexia nervosa.” American Journal of Psychiatry 152, no. 7 (1995): 1073-1074.