Atypical anorexia nervosa may cause significant cardiac instability in teenagers regardless of weight, highlighting the importance of heart monitoring beyond body mass considerations.
Adolescents with atypical anorexia nervosa may face serious heart risk even when they are not underweight, and new research suggests the danger cannot be explained by weight loss alone. In a retrospective comparison of 192 teenagers, researchers found that those with atypical anorexia nervosa had much lower minimum heart rates than peers who had undergone bariatric surgery, despite the surgery group losing more weight and doing so faster. Clinically significant bradycardia, a resting heart rate below 50 beats per minute, was seen in 22.5% of the eating-disorder group and in none of the surgery patients.
The findings matter because previous research has shown that medical instability, including bradycardia and low blood pressure, can occur across a range of body weights in adolescents with anorexia nervosa and atypical anorexia nervosa. A systematic review and meta-analysis published in 2023 concluded that rapid weight loss is an important marker of risk, but not the only factor, while clinical reviews have long noted that cardiac complications are among the most common and serious consequences of restrictive eating disorders.
The new study sets up an unusual contrast. Bariatric surgery patients experienced substantial, medically supervised weight loss after a structured preparation programme, yet they did not show the heart-rate suppression seen in the eating-disorder group. That suggests the context of weight loss matters as much as the amount. The researchers point to baseline weight, nutritional state and hormonal adaptation as likely reasons the two groups diverged. In particular, lower triiodothyronine, or T3, a thyroid hormone linked to metabolism and heart rate, was associated with slower pulse rates, but it did not fully explain the difference between groups.
The study also found that more adolescents with atypical anorexia nervosa reported excessive exercise and purging, but neither appeared to account for the cardiac pattern. Electrolyte levels were similar between the groups, weakening the case for dehydration or purging as the main cause of the low heart rates. Taken together, the results support a cautious approach in clinics: teenagers can be medically unstable from restrictive eating even when their weight remains in the normal range, and heart monitoring should not depend on body mass alone.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
