Normal body weight can hide a type of serious eating disorder in teens and young adults

Patients who suffer from atypical anorexia nervosa are just as ill, medically and psychologically, as those with classic anorexia nervosa, even though their weight is in the normal range


                            Normal body weight can hide a type of serious eating disorder in teens and young adults

Teens and young adults - who have a type of eating disorder called atypical anorexia nervosa - can have normal body weights and still be dangerously ill, both mentally and physically. 

The findings, according to a study led by researchers at the Stanford University School of Medicine and the University of California-San Francisco, suggests that normal body weight can hide this eating disorder, unlike anorexia nervosa, which is characterized by abnormally low body weight. According to the researchers, dangerously low heart rate and blood pressure, as well as severe electrolyte imbalances and psychological problems, are common in patients with atypical anorexia, whose weight is within a normal range. 

“The study demonstrates that adolescents and young adults with atypical anorexia nervosa are just as ill medically and psychologically as those with classic anorexia nervosa, even though their weight is in the normal range. In fact, their scores of disordered eating psychopathology were even higher. They were just as likely to have dangerously low heart rates, unstable vital signs from lying to standing, and life-threatening electrolyte disturbances. We found that weight history and not just the current weight was associated with markers of malnutrition across a range of body weights,” Dr. Neville Golden, professor of pediatrics at the Stanford School of Medicine, and senior author of the study, told MEA WorldWide (MEAWW). Dr. Golden adds, "This group of patients is underrecognized and undertreated.”

Further, says the team, rapid weight loss is the best predictor of medical and psychological problems in patients with atypical anorexia and not their body weight at diagnosis. The findings, published in Pediatrics, shows that the severity of the illness cannot be predicted or assessed by simply relying on a person’s current body weight. “Patients with large, rapid or long duration of weight loss were more severely ill regardless of their current weight,” the findings state.

According to the American Psychiatric Association, eating disorders affect several million people at any given time, most often women between the ages of 12 and 35. The Association defines eating disorders as illnesses in which the people experience “severe disturbances in their eating behaviors and related thoughts and emotions. People with eating disorders typically become pre-occupied with food and their body weight.”

The researchers explain that traditionally, individuals had to be below 85% of their ideal body weight to receive a diagnosis of anorexia nervosa. The disorder is characterized by restrictive eating, over-exercising, distorted body image, and an intense fear of weight gain. 

However, in 2013, a new category of an eating disorder was formally recognized: atypical anorexia nervosa. Individuals with this condition meet all other diagnostic criteria for anorexia nervosa but have normal body weight, says the team. The researchers say that the rapid rise in patients with atypical anorexia nervosa, who require hospitalization at a normal weight, has "challenged reliance on current weight to guide clinical concern."

"The bigger context is that, over the past 30 years, the prevalence of adolescent obesity has quadrupled, and teens are being told to lose weight without being given the tools to do so in a healthy way," says registered dietitian Dr. Andrea Garber.

"Obese teens, who adopt unhealthy behaviors, such as severe food restriction and extreme exercise, may initially be praised for weight loss or told not to worry about eating-disorder concerns because they aren't underweight. By the time they get to see us, they have lost a tremendous amount of weight, their vital signs are unstable, and they need to be hospitalized," says Dr. Garber, who is an adjunct professor of pediatrics at UCSF and the study's lead author. 

According to the American Psychiatric Association, eating disorders affect several million people at any given time, most often women between the ages of 12 and 35. (Getty Images)

The findings

For their research work, the team compared 50 patients with atypical anorexia nervosa with 66 patients who met traditional diagnostic criteria, including being underweight. The participants were 12-24 years old, and 91% were female. All participants received eating-disorder treatment as part of the study.

The researchers found that before developing an eating disorder, patients with atypical anorexia had higher weight-to-height ratios than typical patients. During their illness, patients in both groups lost the same amount of weight, an average of 30 pounds over 15.9 months. 
During the course of the study, the researchers found that the factors that best predicted how severe the illness was included the amount, speed, and duration of weight loss. According to the findings, body weight at the time of diagnosis was not the best predictor.

"The two groups had equally poor vital signs, including low heart rate and low electrolytes. Cessation of menstruation, a side effect of the disease, was equally common in the two groups. Some members of both groups also had very low blood pressure, although this was more common in patients with typical anorexia. Atypical patients had worse psychological  symptoms, on average," says the study.

The researchers recommend further studies to identify what constitutes healthy weight for adolescents recovering from atypical anorexia nervosa. "Assessment of patients with anorexia nervosa traditionally relied on current weight, with the highest index of concern for low weight patients. Our findings support concern for patients with large, fast, and/or long durations of weight loss, even if current weight remains normal. Future research is needed to examine the use of weight history to inform treatment decisions and outcomes," says the study.

According to Dr. Golden, the first step is to be aware of this condition and recognize that someone can have a serious eating disorder even at normal weight. “The next step would be to assess someone who has recently lost a great deal of weight for an underlying eating disorder. In someone who does need to lose weight, guidance should be provided on how to do so in a way that is healthy and sustainable. The patient should be monitored to ensure that they do not lose weight too rapidly and that they do not develop signs of medical instability (such as low heart rate, orthostasis or electrolyte disturbances),” Dr. Golden told MEAWW.

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