Low body weight has long been a key warning sign of anorexia nervosa. However, recent research suggests that relying on body weight to make a diagnosis is risky. In fact, sufferers may have a bodyweight that’s well within normal ranges while anorexia lurks undetected, doing significant damage to their health.

A study conducted by researchers at Stanford University School of Medicine and the University of California-San Francisco has found that anorexia nervosa patients with normal body weights were just as likely to develop complications from the disease as were those patients with below-normal weights. The study concluded that warning signs other than weight were more effective at spotting anorexia cases.

Atypical Anorexia

Before the release of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) in 2013, a diagnosis of anorexia nervosa (AN) required that the sufferer have a bodyweight that was less than 85% of normal. The DSM-5 changed the diagnostic criteria, removing the weight cut-off percentage and focusing instead on a severe restriction of calorie intake that results in low body weight.

More importantly, though, the manual added a disorder called atypical anorexia. Someone with atypical anorexia meets all the diagnostic requirements of anorexia nervosa, except that their body weight stays in a normal range despite their restricted diet.

The Stanford/UCSF study is the most comprehensive comparison to date of patients with atypical anorexia and AN. The study’s results make it clear that patients with atypical anorexia are in just as much danger as those with AN.

“This group of patients is underrecognized and undertreated,” said Neville Golden, MD, professor of pediatrics at the Stanford School of Medicine. “Our study showed that they can be just as sick medically and psychologically as anorexia nervosa patients who are underweight.”

Weight Doesn’t Tell the Whole Story

The study included 116 young patients, most of them young women, who met some diagnostic criteria for anorexia. Fifty of the participants met the criteria for atypical anorexia, and 66 met the criteria for the traditional diagnosis of AN (including the low-weight requirement). The participants’ physical and psychological health was monitored during the study, and all of them received treatment for eating disorders.

Overall, all of the participants lost weight at a similar rate, an average of 30 pounds over the course of the study. Both groups had similar incidences of low heart rate, low electrolyte levels, and cessation of menstruation. There was no indication that those in the low-body-weight group suffered these symptoms to a greater degree.

In some ways, the participants with atypical anorexia fared worse. Patients in this group had, on average, more severe psychological symptoms, and they were also more likely to have low blood pressure.

The Real Warning Signs

If low body weight isn’t the most important red flag for detecting severe anorexia, what is? The researchers used statistical modeling to sort out which factors were the best predictors of negative health impacts. They discovered that body weight is not actually a reliable way to identify severe anorexia nervosa.

The study found that the participants who lost the most weight, lost it the fastest, and suffered from the weight loss over the longest period of time were the ones who experienced the most severe complications of the disease. These factors were more consistent predictors than were the participants’ actual weight ranges.

Changing Perspective

Under the old way of thinking about anorexia nervosa, someone who lost a great deal of weight but stayed within what seemed to be normal bounds was likely to go undiagnosed. In many cases, their weight loss might even be seen as a good thing. But, as this new study confirms, the stereotypical picture of a severely underweight anorexia sufferer is outdated and inaccurate.

Anorexia can hide in plain sight, doing its damage quietly and invisibly. To protect our loved ones’ physical and mental health, we have to move beyond obsolete ideas and be alert to the disease’s real, insidious patterns.

Stanford Medicine, Normal body weight can hide an eating disorder in teens, study finds
Psychology Today, What Is Atypical Anorexia Nervosa?
DSM-IV to DSM-5 Anorexia Nervosa Comparison

Share This Article

You Are Not Alone

For you or a loved one to be diagnosed with a brain or mental health-related illness or disorder is overwhelming, and leads to a quest for support and answers to important questions. UBA has built a safe, caring and compassionate community for you to share your journey, connect with others in similar situations, learn about breakthroughs, and to simply find comfort.

United Brain Association

Make a Donation, Make a Difference

We have a close relationship with researchers working on an array of brain and mental health-related issues and disorders.  We keep abreast with cutting-edge research projects and fund those with the greatest insight and promise.  Please donate generously today; help make a difference for your loved ones, now and in their future.                                                                 

The United Brain Association – No Mind Left Behind

Share Your Story

If you have an experience, a story, or someone in your life you want to recognize for their strength and willpower, please share it with us. We want to hear from you because listening is part of healing.

Connect With Us

Receive news on Brain Awareness, the Latest Research, and Personal Stories