Caring for offspring diagnosed with eating disorders (EDs) entails being under high chronic stress, with negative consequences for health. However, most previous research has only evaluated self‐report measures of health, biological markers being poorly studied. In this regard, the evaluation of the cortisol awakening response (CAR) could add significant information about the biological basis of health disturbances in this population. The main aim of the present study was to compare CAR and self‐reported health between informal caregivers (ICs) of people with EDs and non‐caregivers. Furthermore, we explored the effect of the nature of the diagnosis, comparing ICs of people with anorexia and bulimia nervosa. ICs had a blunted CAR, and more anxiety and insomnia, and social dysfunction, together with poorer perceived general health than non‐caregivers. ICs of people with anorexia nervosa had higher levels of morning cortisol and burden, and more social dysfunction and severe depression than those of people with bulimia nervosa. Our results demonstrate marked health problems in ICs of people with EDs, especially when the care recipient has anorexia nervosa. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.