Researchers say these metabolic abnormalities may not be symptoms of the eating disorder. They may be part of the cause.
Anorexia may not be a purely psychological disorder.
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Anorexia nervosa is an eating disorder that causes a distorted perception of one’s weight.
This can lead to extreme weight control behaviors that result in starvation.
The study’s findings may help guide future research toward more effective treatments for this sometimes lethal illness.
Details of the study are published in the journal Nature Genetics.
A multinational group of more than 100 researchers contributed to the study.
Data came from Anorexia Nervosa Genetics Initiative and the Eating Disorders Working Group of the Psychiatric Genomics Consortium.
The researchers analyzed the DNA of nearly 17,000 people with anorexia and 55,000 people without the condition.
The researchers identified eight genetic variants linked to the disorder.
They also found that the genetic basis of anorexia overlaps with obsessive-compulsive disorder, depression, anxiety, and schizophrenia. Genetic factors associated with anorexia also affect physical activity.
Some of the metabolic abnormalities of people with anorexia have been thought to be due to starvation.
The researchers say those abnormalities may actually contribute to the development of anorexia — that the origins of the disease may be both metabolic and psychiatric.
They suggest the “exceptional difficulty” people with anorexia have in maintaining a healthy weight may be partly due to “fundamental metabolic dysregulation.”
Considering both these risk factors could eventually lead to improved treatment.
Dr. Mir Ali is a general and bariatric surgeon at MemorialCare Orange Coast Medical Center in California.
He told Healthline the new study was well done.
“Anorexia is not an easy problem to fix, and it has a high mortality rate because many patients continue to deteriorate over time,” Ali said.
He says the body has a metabolic set point.
When your metabolism isn’t regulating properly, your set point can end up too high or too low. When that set point is too low, the body naturally doesn’t want to gain weight, he explains.
“We see people who swear they hardly eat but gain weight, and we don’t have a good explanation for that. We do see patients who eat but have trouble gaining weight. Their metabolism allows them to do that,” Ali said.
Thomas B. Hildebrandt, PsyD, is associate professor of psychiatry at Icahn School of Medicine and chief of the division of eating and weight disorders at Mount Sinai Hospital in New York.
He told Healthline there’s a lot of mystery associated with anorexia.
“This landmark study identified a range of potential targets for illness. It highlights what clinicians have known for a long time: It’s not just a psychiatric illness. There are metabolic and other targets as well. It’s a major step in the road map toward identifying the basic neurobiology of the disease,” Hildebrandt said.
He notes eating disorders tend to run in families. Some of that is genetic, but there’s the food environment and other environmental factors as well.
“To some degree, we think that temperamental characteristics may influence the psychopathology. You have a vulnerability to anorexia nervosa, and you also have an environment that is hypercritical or puts a lot of pressure on you for physical activity, or otherwise can activate that vulnerability,” Hildebrandt explained.
Someone with anorexia may limit the foods they eat to the point of starvation. They may also engage in intense exercise in an effort to burn more calories.
Treatment usually involves medical care for physical problems caused by poor nutrition and starvation, along with mental health care.
According to the National Association of Anorexia Nervosa and Associated Disorders, 30 to 35 percent of people with anorexia have a comorbid mood disorder, such as depression. About 50 percent have comorbid anxiety disorders.
Psychiatric medications may help with these coexisting disorders. However, there are no approved medications for the treatment of anorexia.
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Part of the problem in treating anorexia is the stigma.
“People with anorexia don’t feel they deserve help. And because of the way the illness presents itself, it alienates family, caregivers, and even the primary care physician telling you to gain weight. It can frustrate the mental health provider trying to help you think differently about gaining weight, but you can’t, because it just doesn’t feel right,” Hildebrandt said.
He adds that particularly for adolescents, the family-based approach has the most potent effect.
That means interventions that engage family members and loved ones in maintaining nutrition.
Intensive residential and inpatient programs are good at helping people gain weight, says Hildebrandt.
“They take hold of the environment completely and basically give you no choice but to get healthy in order to get out. It’s considered a safe environment for a majority of people who go through it,” he said.
The downside to all that safety and containment, says Hildebrandt, is that you can’t replicate it in everyday life.
“There’s something else outside of psychiatric symptoms that make it much harder to get people to a healthy weight and keep them there. Interventions, while lifesaving, are really only temporary. That’s the place our field is at. Temporary solutions for a chronic illness,” Hildebrandt said.
Ali is hopeful this could open up a whole new avenue of treatment.
“There’s a lot of research going on in both directions, for both underweight and overweight people. A few hormones seem to be well understood, but for the most part, we just don’t know all the hormones involved and how they interact together to set somebody’s weight,” he said.
“So many different things play a role in setting somebody’s weight. It’s clear that metabolic profile can affect that in one direction or the other,” Ali added.
“If we can identify that they’re missing some critical hormone or critical element that could possibly be replaced, along with psychological counseling, it could help patients overcome the disease,” he said.
How we look at anorexia is already changing.
Once thought of as a female disorder, we now understand that males also develop anorexia.
“It’s part of the stereotype, plain and simple,” Hildebrandt said. “It might look slightly different because males carry more lean muscle mass. Historically, it’s been near impossible for men to find treatment outside a handful of places. That’s changed, particularly in the last five years. Now you see more inclusivity.”
He hopes the knowledge that anorexia may be physical as well as mental will help reduce the stigma.
As far as finding a new treatment, Hildebrandt cautions that it’s going to take time.
“The study is a road map, a place to start in terms of the fundamental biology of the illness. While technology is getting more robust and faster all the time, we still have a long search ahead before we get to therapeutics.
“Drug discoveries build around the idea of lots of failures for one success. We still have to figure out how to help someone in the real world, and it’s a challenge,” Hildebrandt said.
