Adolescents and young adults with anorexia nervosa whose weight is in the healthy, overweight or obese ranges face similar cardiovascular and other health complications as their counterparts with low body mass index (BMI), according to a new study led by researchers at University of California, San Francisco (UCSF).

The study, led by Andrea Garber, PhD, RD, chief nutritionist for the UCSF Eating Disorders Program, compared weight loss and illness severity among two groups of patients aged 12 to 24 who had been enrolled in a clinical trial upon admission to the hospital for treatment: 66 with anorexia nervosa, which excluded those who were severely underweight, and 50 heavier patients with so-called atypical anorexia nervosa. 

They found that patients with atypical anorexia nervosa are as likely as underweight patients to suffer from bradycardia, or slow heart rate, a key sign of medical instability that can lead to irregular heartbeat and other complications. These patients also may carry a heavier psychological burden than those who are underweight, due to heightened preoccupations with food avoidance and more negative feelings about body shape and weight. 

Keys to Determining Illness Severity

“Lower weight has been traditionally equated with more severe illness,” said Garber, who is a professor of pediatrics in the Division of Adolescent Medicine at UCSF Benioff Children’s Hospitals. “Currently, one-third of eating disorder admissions are patients with atypical anorexia nervosa at normal weight or above. 


“Our study suggests that patients with large, rapid or long duration of weight loss are more severely ill, regardless of their current weight.” –Andrea Garber, PhD, RD


“Our study suggests that patients with large, rapid or long duration of weight loss are more severely ill, regardless of their current weight,” she said, noting that both groups lost about 30 pounds over approximately 15 months. 

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), the latest version of the “bible” of psychiatry, atypical anorexia nervosa fulfills the criteria for anorexia nervosa: food restriction leading to weight loss, intense fear of gaining weight and “disturbance in the way in which one’s body weight or shape is experienced.” The single exception is that the weight of the patient with the atypical variant is within or above the normal range, despite significant weight loss.

In the study, the average BMI for the typical group at their heaviest was 20.7 kg/m2, at the low end of the healthy range, and 25.2 kg/m2 for the atypical group, at the low end of the overweight range. By the time they were admitted to the hospital, the typical group’s average BMI was 15.7 kg/m2 and the atypical group’s average BMI was 19.4 kg/m2. In terms of weight, for a 5’6” female aged 16.5 years – the average age of the participants – this translates to 97.9 pounds (44.4 kg) for the typical group and 121.8 pounds (55.3 kg) for the atypical group. 

The participants were enrolled in the StRONG trial, a study of refeeding, or short-term nutritional rehabilitation, at UCSF Benioff Children’s Hospital San Francisco and Lucile Packard Children’s Hospital, Stanford. Of the 116 participants, 105 were female; half were white in the atypical group and two-thirds were white in the typical group. The study was published in the journal Pediatrics

The study found that female atypical patients were just as likely as their underweight counterparts to stop menstruating, a hallmark of hormone suppression due to poor nutrition that impacts fertility and bone density. Both typical and atypical patients were susceptible to electrolyte imbalances from inadequate sodium, potassium, calcium and chloride intake, which can impact the brain, muscles and heart functioning. 

Patients in the atypical group scored significantly higher in a questionnaire that assessed eating disorder psychopathology, which addressed issues such as avoidance of food and eating, preoccupation with calories and eating in secret, feelings of fatness and discomfort seeing one’s body, dissatisfaction with weight and reaction to being weighed. The atypical group’s global score reached 3.8, compared with 3.0 for the typical group. For context, scores in community-based women are less than 1.0. 

“One possibility for the more extreme eating disorder behaviors and cognitions among the atypical group is that some of the patients had overweight and may have suffered stigma or teasing that made them feel worse about their size,” said Garber. “Or, if they were genetically predisposed to be on the heavier side, they may have had to employ more severe behaviors or have more severely disordered thoughts in order to fight their biology.”

What the Research Means to Health and Exercise Professionals

“These findings show that atypical anorexia nervosa is a real illness, not just a lesser form of ‘pre-anorexia nervosa,’” explains Garber, who suggests that healthcare providers need to keep a watchful eye for individuals with large or rapid weight loss, even if they were heavier to begin with and now appear to be “normal.” Similarly, health and exercise professionals are in a position to potentially spot behaviors that might be viewed as extremely disciplined, especially where weight loss is concerned, but are actually unhealthy when taken to the extreme.

Recognizing the signs of an eating disorder and knowing where to refer for help are among the most important things you can do for a client struggling with food and body-image issues. This article offers guidance on the signs of some specific body image–related health concerns that may be especially evident in an exercise environment, as well as advice on how to handle these difficult client conversations. Treatment usually involves a multidisciplinary approach between the individual’s medical provider, mental health specialist and a registered dietitian. With appropriate treatment, those with eating disorders are able to begin their road to recovery and eventually lead healthy and more fulfilling lives. For further information and resources in your area, contact the National Eating Disorders Association