Anorexia Invokes the Human Genetic Response to Starvation

Anorexia and restrictive eating disorders present a very confusing medical picture for doctors and patients alike. Other eating disorders lead to clear medical problems easily diagnosed by physical exam and blood tests, but anorexic patients appear erroneously healthy by labs. Once the blood tests finally become abnormal, the patients are extremely ill. This confusion leads people to minimize the effects of starvation for far too long.

Because doctors never see starving patients except for people with anorexia, they have limited knowledge of how the body survives in these circumstances.

However, the human body has a long history of adaptation to starvation. Long before the world of abundant food we live in now, famine was a reality of human life. The laws of natural selection meant that people who genetically were programmed to survive famine would live. Examples of adaptations are slowed metabolism, conservation of energy and preservation of necessary organ function all in the face of prolonged starvation.

These genes to survive famine have been passed down through generations even though many cultures have more than enough food. For the large majority of people, their genetic response to starvation is never tested unless they start to diet severely or develop an eating disorder.

The primary method the body uses to survive famine is through homeostasis, maintenance of normal blood concentrations of all blood cells and electrolytes. Clearly, starvation will affect the amount of blood cells and electrolytes available to the body. Limited food supply means much decreased intake of electrolytes, and malnutrition leads to an inability to produce sufficient blood cells.

But blood tests do not measure amounts but instead concentrations. The body adapts by shrinking down blood volume which means that concentrations remain the same while amounts of blood cells and electrolytes diminish significantly. 

Blood levels remain stable which masks the worsening of the person’s health. If someone has fewer red blood cells, that person becomes anemic, even if the blood tests appear normal.

Education of doctors and patients can decrease the chance that people will ignore the worsening medical condition of a patient and not be fooled by the body’s genetic ability to survive starvation. Early intervention and treatment can help people with anorexia avoid getting severely ill.