Heart Rates and Eating Disordersby Mark Warren, M.D.
By Dr. Mark Warren, chief medical officer at The Emily Program
One area that is a constant concern with those with eating disorders has to do with heart rate, in particular, low heart rate. This issue is generally observed at low body weight but can happen anytime there has been a significant amount of weight loss. In general, as one loses weight one loses muscle mass. With the loss of muscle mass there may be loss of heart mass as the heart is a muscle.
The body, being generally wise, will try to preserve the heart as long as it can, but under the stress of continued weight loss or malnutrition wasting of the heart muscle can occur. Initially the heart may beat more quickly to compensate for being a smaller size, but this is quite exhausting for the heart and ultimately can lead to further damage. To conserve heart muscle and thus keep the entire body functioning as well as possible there will be a slowing of heart rate, called bradycardia. Bradycardia can be very dangerous and is one of the leading causes of illness, hospitalization, and death for those with eating disorders. Heart rates in the 40s or lower are particularly dangerous. As heart rate goes down the risk of arrhythmia, or abnormal rhythm of the heart, becomes more likely. A heart rate in the 40s will often fall into the 30s while asleep, thus increasing these risks. This is why clients with heart rate in their 40s will be hospitalized, both for safety in the moment and for overnight monitoring.
Sometimes there is confusion about the relationship of heart rate and exercise. Many patients erroneously believe, and are told, that a low heart rate is evidence of being an athlete. There are no studies showing that significant and rapid weight loss is normal for an athlete or healthy for the heart. The confusion usually results from the fact that, in general, athletes with low heart rates have low heart rates because they have gained significant muscle mass, including mass in their heart, and their heart does not have to beat as often to provide adequate oxygen and blood for the body. This is most definitely not the case in situations of weight loss, starvation and smaller than normal hearts. One should never assume that in the presence of an eating disorder that a low heart rate has anything to do whatsoever with athletic ability. A low heart rate is almost always due to the illness itself. The good news is that with cessation of physical activity, increase in food intake, and restoration of normal weight the heart can recover completely. The resolution of the illness can include lifelong heart health.