The side effects of eating no food, whether because of lack of access to food, self-imposed starvation or fast, or eating disorder, can be damaging both physically and mentally. When people fail to take in food, their bodies start to break down fat to use for energy. When fat runs out, the body starts to break down other vital tissues, muscles and internal organs, leading to serious health complications and potentially death.
Loss of Body Fat
Those who do not consume enough food can lose substantial amounts of body fat. In addition to overall weight loss, fat is lost in the face, giving it a sunken appearance. Skin can become dry, inelastic, pale and cold to the touch. Bones may protrude through the skin, and a wasting away of both muscle and fat tissue may occur (a condition called cachexia). With the loss of extreme amounts of body fat, women can lose their ability to menstruate and become infertile. A condition called ketoacidosis can also develop as a result of the body rapidly burning fat to get its energy. High levels of acid can build up in the blood, potentially leading to coma or death.
Malnutrition and Dehydration
Without food, people are at serious risk of malnutrition due to their failure to take in vital protein, vitamins and nutrients. Dehydration can also occur without sufficient intake of carbohydrate and fats. Symptoms of dehydration include dizziness, weakness, and a darkening of the urine. Malnutrition and dehydration can lead to serious, sometimes fatal conditions like respiratory infections, blindness, kidney failure, seizures and heart attack.
When levels of electrolytes like sodium, potassium, calcium and magnesium get too high or too low, bodily organs stop functioning as they should. The malnourished person will have trouble maintaining healthy teeth, joints and bones and stable blood sugar levels. Nerve and muscle impulses will also be affected, and the kidneys and heart may be damaged because they are unable to perform normally. Some may experience edema, or swelling, because the kidneys cannot rid the body of excess sodium.
Vitamin and Mineral Deficiencies
Deficiencies in essential vitamins and trace minerals can cause the body to deteriorate in a number of ways. People who fail to eat may begin to lose their hair, and what hair they do retain may become sparse, dry and brittle. Their nails will also become brittle, and their skin will feel dry and tough. Some may develop a condition known as lanugo in which soft, downy hair begins to grow on the face, arms and back.
Mental and Behavioral Side Effects
Not taking in food can lead to problems with mental functioning and disturbances in mood and behavior. Side effects such as insomnia, fatigue, hyperactivity, irritability, apathy, and unresponsiveness (stupor) may occur. Low blood sugar (hypoglycemia)--another side effect of not eating--can also cause mental deterioration.
Blood Pressure Problems
Sometimes as a side effect of starvation-induced electrolyte imbalances and vitamin and mineral deficiencies, problems with blood pressure can occur. A person may develop low blood pressure (hypotension), high blood pressure (hypertension), or orthostatic hypotension (sudden drop in blood pressure upon sitting or standing).
Blood Sugar Problems
People who do not eat enough food may develop serious problems in regulating their blood sugar caused by hormonal imbalances. They may become hypoglycemic (low blood sugar), hyperglycemic (excessive blood sugar), or even diabetic. These conditions can lead to problems with the liver or kidneys, and circulatory, neurological and immune problems.