Rethinking Eating Disorders

Posted: May 4, 2022
Rethinking Eating Disorders

Dr. Cynthia Bulik's research reveals these psychiatric disorders also have a crucial metabolic dimension

2017 BBRF Distinguished Investigator Cynthia Bulik, Ph.D., is one of the world’s foremost experts on eating disorders (EDs)—anorexia nervosa, bulimia nervosa, and binge-eating disorder. A clinical psychologist and researcher, she has devoted her decades-long career to treating and studying all three EDs.

The Distinguished Professor of Eating Disorders at the University of North Carolina and founder of UNC’s Center of Excellence for Eating Disorders, as well as Director of the Centre for Eating Disorders Innovation at Sweden’s Karolinska Institute, Dr. Bulik arguably has done as much as any figure in the medical and research communities to sharpen our understanding of the origins and causes of eating disorders.

In addition to the 660 scientific papers and 60 chapters she has authored, she has devoted considerable effort to communicating directly with the public as the author of seven books, containing specific advice for patients and families. In the process she has helped to raise awareness about what she and other experts suggest is a set of persistent and damaging myths about these life-threatening conditions.

Myths and misunderstandings about eating disorders, in fact, have been so pervasive, and have proved such an obstacle to understanding their underpinnings in medical and scientific terms, that Dr. Bulik prefers not to talk about them at any length. “Every time we mention them, it only tends to reinforce them,” she says.

One in particular is probably familiar to most people: the popular notion of eating disorders, and especially anorexia, as affecting women and “caused” by powerful societal pressures for women to be thin.

Is there no truth in that popular conception of anorexia? Societal attitudes about femininity, thinness, and body image are by no means irrelevant, Dr. Bulik makes clear. But years of research in the clinic with patients, and in the laboratory, studying the genetics of eating disorders, leads her and others to stress the causal interplay of environmental factors and underlying biological factors that drive symptoms.

Indeed, Dr. Bulik’s recent research has led her to suggest a fullscale “reframing” or re-conceptualization of eating disorders. Her most influential contribution has been to suggest that EDs not only have psychiatric roots but also roots in malfunction of the body’s metabolic systems, which regulate how energy (sourced, ultimately, in food) is supplied to our organs.

To help combat myths about EDs, Dr. Bulik and colleagues at the Academy for Eating Disorders published the “9 Truths” document, based on a talk given by Dr. Bulik in 2014.

While the “9 Truths” document doesn’t provide statistics, the National Institute of Mental Health, citing research conducted between 2001 and 2003, estimates that the lifetime prevalence of anorexia in women is a bit less than 1 in 100, and in men about 1 in 300. “Past-year” prevalence statistics from 2001–2003 were not available for anorexia, but were for bulimia, which affected 1 woman in 200 and 1 man in 1000. Binge-eating disorder was more common, affecting 1.6 per 100 women and 0.8 per 100 men annually between 2001 and 2003. Prevalence of EDs is much higher in young people, the NIMH statistics suggest. For the years 2001–04, estimated prevalence of EDs in adolescents was 2.7 per 100: 3.8 per 100 females and 1.5 per 100 males.

“Instruments we have to clinically assess eating disorders have been built around the way females ‘present’ them,” Dr. Bulik explains. “One of the most famous questionnaires asks for responses to statements like, ‘I’m satisfied with the size of my hips’ or ‘I like the size of my breasts.’ “Men with anorexia will often say they are in pursuit of “leanness,” or “low body fat” or “being ripped” rather than “thinness,” Dr. Bulik notes. “It is likely that more women than men have EDs, but I think we’re missing a lot of men just because of the way we diagnose.”

Regarding the cultural value placed on thinness: Dr. Bulik acknowledges that this obsession so powerfully disseminated via advertising and now reinforced via shaming and bullying on social media, is certainly an important part of the story. For the sake of clarity, she notes that cultural attitudes about thinness are an environmental factor in causation. Her research addresses eating disorders at the level of genes, cells, and regulatory systems of the body and how they interact with environmental factors.

As a scientist and physician, one specific question that motivates Dr. Bulik is to ask why, if the messaging about thinness in our culture is essentially ubiquitous, only some individuals develop an eating disorder. Research on the biological side of the question seeks to discover what it is about these individuals that distinguishes them or places them at high risk.


There is a counterintuitive dimension in eating disorders, Dr. Bulik points out, which has led her to crucial insights. Why would any person deprive him or herself of food, to the point that they risk ruining their health and even dying?

“I think in the beginning,” she says, “something has to be reinforcing about starvation in order for a person to persist in doing it. Because for the rest of us, who don’t have this disorder, being hungry is not something we crave, not something we seek. It is not, in the language of psychiatry, ‘reinforcing.’”

A remarkable fact was clear to Dr. Bulik as she treated patients with anorexia. She realized, “There is something about that first time or second time that they fasted and they realized: ‘Oh, this feels good. I’m going to do this again.’” This elevated feeling, akin to a “high,” is not only recollected by people diagnosed with anorexia; it can also be experienced by those with bulimia and binge-eating disorder, who sometimes restrict their food intake in between periods of binge eating. One contrast is that in the case of people with BN and BED, “their bodies don’t seem able to maintain that [fasting] state, so they follow these periods with binges.”

Are the three disorders connected? If so, in what way does environment interact with biology ? To help explain how, Dr. Bulik proposes that we consider a representative sample of young people of both sexes, all of whom are exposed not only to cultural messaging about weight, body shape, and fitness in advertising and social media, but who in this example receive a direct challenge from an authority figure to go on a diet, regardless of whether they are underweight, normal weight, or overweight.

“Imagine you have a classroom filled with 12-year-olds,” Dr. Bulik posits. “Believe it or not, this actually happens: the teacher decides to go on a diet and invites the class to do the same. So they all decide to reduce their calorie intake by 40% on Monday and see how they feel later in the week.”

“By Wednesday, most of the students will say, ‘This is ridiculous. I want some pizza and ice cream. I’m moving on.’ For a couple of the kids, the 2 or 3 days of caloric restriction ends in a sensation of their body screaming out: they don’t just want a slice or two of pizza and an ice cream cone; they eat a whole pizza and a half-gallon of ice cream. These are the children who are binge-prone. Then, there is one young person, maybe two, in the class who realize that being asked to go on that diet has been a watershed moment in their life. They say to themselves, ‘Wow, this is awesome—and I’m good at this. I can do this and none of the others can. I also feel less anxious than I usually do.’ These are the young people at risk for developing anorexia.”

“This echoes something that so many of the parents we’ve worked with have told us. They say: ‘It was as if from one day to the next our child was hijacked—as if they became a different person.’“


What is really happening when a young person becomes conscious of deriving pleasure or satisfaction from extended caloric self-deprivation? Dr. Bulik explains it in terms of energy balance in the body. “People who maintain their weight can be thought of as being in energy balance; they are expending about the same amount of energy as they are consuming. People who are gaining weight are in positive energy balance, meaning they’re eating more than they’re expending. On the other hand, repeated fasting or consistent food restriction puts one in a position of negative energy balance—you’re not consuming enough to match the body’s energy needs and so your weight begins to decline.”

Those whose initial experience of dieting is accompanied by a high or feeling of satisfaction and then seek to repeat the behavior are at great risk of developing an eating disorder, according to Dr. Bulik. In the “restrictive” subtype of anorexia, the individual enters a potentially lifethreatening state of negative energy balance. Those with anorexia who also binge and purge, as well as those who develop bulimia, experience energy imbalance in varying ways and degrees—depending on how much of their food intake they feel compelled to purge. People with binge eating disorder who in most (but not all) cases do not purge or otherwise “compensate” for excessive food intake can enter a state of positive energy balance and gain weight—although the term “positive” in this context is not to be confused with “desirable” since binge eating involves a dangerous loss of control over food intake.


The next question is how to understand why different individuals enter different energy-balance states. In 2018 and 2019, Dr. Bulik, heading a large international consortium, published influential papers reporting on what at the time was the largest genetic study of anorexia. This provided major new insights about anorexia and metabolism.

Results of the genome-wide association study (GWAS) identified eight areas in the human genome in which DNA variations are likely to contribute to risk for the illness. Unsurprisingly, it provided evidence that anorexia shares genetic factors with other psychiatric disorders including obsessive-compulsive disorder, anxiety, major depressive disorder, and schizophrenia.

But the GWAS data also contained a surprise. It revealed a significant correlation between the genetics of anorexia nervosa and metabolic traits. One key correlation was in body mass index, or BMI. As a result of restricting caloric intake and increasing energy expenditure, patients with anorexia nervosa typically have low BMIs. But studying the genomes of people with and without anorexia revealed that some of the same genes that increase someone’s risk of developing anorexia nervosa also decrease their risk of having a high BMI. The same pattern was seen with Type 2 diabetes (T2D): genetic factors that place you at greater risk for developing anorexia put you at lower risk of having T2D. The processes in the body that normally regulate metabolism, including weight regulation and energy balance, may be malfunctioning in people with anorexia nervosa, underlying some of the weight and feeding symptoms that have previously been explained as purely psychological.

Not only do these results argue for treating anorexia as a metabolic disorder as well as a psychiatric one; they also have implications for the problem of severe stigma. Among the ways in which anorexia has been misunderstood, Dr. Bulik says, is that contrary to common belief, “patients often want to eat and desperately want to get well, but they find it enormously difficult to do so.” The genetic data can help explain on a metabolic level why, even after hospital-based weight restoration, patients with anorexia often rapidly lose weight again after discharge.

These findings, therefore, should help parents and loved ones understand that recovery is not simply a matter of “deciding” to eat more. As Dr. Bulik puts it: “For patients, recovery from anorexia nervosa is fighting an uphill battle against their biology and patients need our support in doing so.”

The metabolic dimension of anorexia indicated by genome analysis has not yet been replicated in bulimia and binge-eating disorder. A consortium led by Dr. Bulik is working on a new, larger GWAS of anorexia nervosa and a GWAS of binge eating behavior. Results are due this summer. In the interim, she is leading a major international effort called the Eating Disorders Genetics Initiative (EDGI), which is conducting the largest study of genetic and environmental risk factors on all three major eating disorders.


The genetic link between BMI and anorexia that has been established has other potential implications. One pertains to a question that Dr. Bulik says she has been asked for years: “Is anorexia the opposite of obesity?”

It now appears to her that anorexia and obesity may be, to some extent, “metabolic bookends,” conditions at opposite ends of a continuum. “On the high end of the weight spectrum, it’s well known that it is fairly easy to get someone to lose weight, but that over time following weight loss, it’s as if their bodies pull them back up to that higher weight. This happens even after bariatric surgery for many people. And of course, it’s very common that we blame the patient—they’ve regained the weight because they lacked willpower or self-control.

“At the other end of the weight spectrum we see the exact same thing. You take someone with severe anorexia—it’s fairly easy to get them to gain weight in the hospital. But so often after discharge, their bodies pull them right back down to that low weight again.” Importantly, she says, “We really do our patients harm when we attribute blame for relapse on their choice or their willful behavior. That’s the core import of the ‘bookend’ concept: we need to look metabolically and biologically why it is that when someone with anorexia or obesity loses or gains weight after seemingly effective treatment, they so often seem to relapse. In most cases, it is not a choice they are making. At least in part, the problem is the body’s difficulty regulating energy balance or a natural inclination for the body to go off the rails and not keep energy balance within healthy parameters.”


In two editorials published in 2021, one in JAMA Psychiatry, the other in the American Journal of Psychiatry, Dr. Bulik and a colleague called attention to “a crisis in care” for patients with anorexia. Mostly due to stigma, many patients are symptomatic for years before seeking treatment. No medications have specifically been developed to treat anorexia, and while some, like the SSRI antidepressant fluoxetine (Prozac), have been prescribed for some patients, they are not often effective, especially when given to patients already at low weight. Cognitive Behavioral Therapy is the most frequently successful treatment, but the overall relapse rate for adult anorexia patients is about 50%.

In recent years, a proliferation of privately run treatment programs for anorexia and other eating disorder patients has contributed to the closing of eating disorders programs in a number of academic medical centers, Dr. Bulik reports. Private-sector treatment tends to be available only for the affluent, as it is not often covered by insurance. And those who do enter such programs, like those in hospitalbased programs, in Dr. Bulik’s view, tend to be released too soon, after attaining 80% of “ideal body weight.”

“This does not mean that recovery isn’t possible,” Dr. Bulik stresses. There is a window of 60 or more days after discharge from acute weight-restoration treatment during which risk of relapse is highest; it declines afterward. For this reason, Dr. Bulik advocates for “a fully integrated step-down model” of care for recovering anorexia patients in which renourishment is followed by participation in a residential treatment program or day program, and then intensive outpatient treatment followed by a less intense phase of such treatment. The key, in her view, is not to release patients from treatment after attaining “80% of ideal weight”— given what has been learned about the tendency of the body to return to a state of negative energy balance and relapse.


New frontiers in research may translate in the coming years into much more effective and specific treatments for eating disorders. It is useful, Dr. Bulik says, to begin looking at the intestinal microbiome—the collection of microorganisms that each of us carries in our digestive system. “When you starve yourself,” she says, by way of example, “you are also starving your bugs. This likely accounts for the lower diversity of microorganisms that we see in people with anorexia nervosa.”

“One question we have is whether the remaining bugs that can tolerate a starvation environment actually contribute to perpetuating the illness. They may not react well when exposed to high-fat foods, for example. Also, there is constant communication between the gut and the brain, and we wonder about the extent to which an impoverished microbiome may seek to perpetuate itself by sending signals to the brain to, in essence, ‘keep up the starvation.’“

Other recent research has indicated that the shape and function of the digestive system changes in people with eating disorders, and those changes may be a factor in explaining why it is so hard to renourish anorexia patients. The lining of the digestive system may lose some or much of its capacity to absorb nutrients. Various expedients have been proposed and are already being tested in preliminary research, using animal models: targeted probiotics, even fecal transplants (which can reintroduce new microorganisms to the microbiome).

A final point stressed by Dr. Bulik is “the importance across the three disorders, of regular eating.” The aim, she says, is to try to restore regular eating: breakfast, lunch, dinner, timed snacks. “Because whether you have anorexia, bulimia or binge-eating disorder, if you are human, your body loves predictability. So restoring regularity is, in a sense, at the core of treatment across the three disorders.” Among other ideas, Dr. Bulik and colleagues are experimenting with wearable technology like the Apple Watch to detect biometric signs of high risk for, say, binge-eating, accompanied by an alarm or text reminder to the patient.

Regarding the pace of much-needed change, Dr. Bulik comments: “Some people say we’re paddling as fast as we can in research, but I challenge that. Our treatments haven’t come very far in the past 20 years. It’s not about how fast we paddle, it’s about finding new ways of paddling to advance our understanding, improve outcomes, and eliminate mortality from these life-impairing illnesses.”

Written By Peter Tarr, Ph.D.

Click here to read the Brain & Behavior Magazine's May 2022 issue