Starvation is the result of a lack of nutrients needed for life to be maintained. Adequate nutrition includes two important parts -- nutrients and calories. It's possible to eat what seems to be enough food without getting the required calories. For example, marasmus is the result of a diet that is deficient mainly in energy.

Starvation is caused by a number of factors. They include:

• Anorexia nervosa
• Fasting
• Coma
• Stroke
• Famine
• Poverty
• Severe gastrointestinal disease

Since the body will combat malnutrition by breaking down its own fat and eventually its own tissue, a whole host of symptoms can appear as starvation sets in.

Children who are chronically malnourished begin to grow much more slowly; anemia is the first sign to appear in an adult. Swelling of the legs is next as protein levels in the blood decrease. Loss of resistance to infection follows next, along with poor wound healing. There is also progressive weakness and difficulty swallowing, which may lead to inhaling food. At the same time, the signs of specific nutrient deficiencies may appear. Characteristic symptoms of starvation include:

• Shrinkage of vital organs, such as the heart, lungs, and ovaries or testes
• Chronic diarrhea
• Anemia
• Reduction in muscle mass
• Weakness
• Low body temperature
• Decreased ability to digest food
• Irritability
• Immune system problems
• Swelling
• Decreased sex drive

If the degree of malnutrition is severe, the intestines may not tolerate a fully balanced diet; in fact, they may not be able to absorb nutrients at all. Carefully prepared elemental diets or intravenous feeding is the first step in treatment. Gradually, solid foods are introduced and a daily diet of 5,000 calories or more is begun.

People can recover from severe degrees of starvation, but children may suffer from permanent mental retardation or growth defects if their lack of food was long and extreme.