Malnutrition

# Overview
Malnutrition is a general term for a medical condition caused by an improper or insufficient diet. It most often refers to undernutrition resulting from inadequate consumption, poor absorption, or excessive loss of nutrients, but the term can also encompass overnutrition, resulting from overeating or excessive intake of specific nutrients. An individual will experience malnutrition if the appropriate amount of, or quality of nutrients comprising a healthy diet are not consumed for an extended period of time. An extended period of malnutrition can result in starvation, disease, and infection.
Malnutrition is the lack of sufficient nutrients to maintain healthy bodily functions and is typically associated with extreme poverty in economically developing countries. It is a common cause of reduced intelligence in parts of the world affected by famine.  Malnutrition as the result of inappropriate dieting, overeating or the absence of a "balanced diet" is often observed in economically developed countries (eg. as indicated by increasing levels of obesity).
Most commonly, malnourished people either do not have enough calories in their diet, or are eating a diet that lacks protein, vitamins, or trace minerals. Medical problems arising from malnutrition are commonly referred to as deficiency diseases. Scurvy is a well-known and now rare form of malnutrition, in which the victim is deficient in vitamin C.
Common forms of malnutrition include protein-energy malnutrition (PEM) and micronutrient malnutrition. PEM refers to inadequate availability or absorption of energy and proteins in the body. Micronutrient malnutrition refers to inadequate availability of some essential nutrients such as vitamins and trace elements that are required by the body in small quantities. Micronutrient deficiencies lead to a variety of diseases and impair normal functioning of the body. Deficiency in micronutrients such as Vitamin A reduces the capacity of the body to resist diseases. Deficiency in iron, iodine and vitamin A is widely prevalent and represent a major public health challenge. An array of afflictions ranging from stunted growth, reduced intelligence and various cognitive abilities, reduced sociability, reduced leadership and assertiveness, reduced activity and energy, reduced muscle growth and strength, and poorer health overall are directly implicated to nutrient deficiencies. Also, another, although rare, effect of malnutrition is black spots appearing on the skin.
Hunger is the normal psychological response brought on by the physiological condition of needing food. Hunger can also affect the mental state of a person, and is often used as a metonym for general undernourishment.

# Causes of Malnutrition
- Famine
- Poverty
- Digestive disease
- Malabsorption
- Depression
- Anorexia nervosa
- Bulimia nervosa
- Untreated diabetes mellitus
- Fasting
- Coma
- Alcoholism and other certain drug addictions
- Over-consumption of fat and sugar
- Overpopulation
- Industrial food processing

# Statistics
Number of undernourished people (million) in 2001-2003, according to the FAO, the following countries had 5 million or more undernourished people :
Note:  This table measures "undernourishment", as defined by FAO, and represents the number of people consuming (on average for years 2001 to 2003) less than the minimum amount of food energy (measured in kilocalories per capita per day) necessary for the average person to stay in good health while performing light physical activity. It is a conservative indicator that does not takes into account the extra needs of people performing extrenous physical activity, nor seasonal variations in food consumption or other sources of variability such as inter-individual differences in energy requirements.
Malnutrition and undernourishment are cumulative or average situations, and not the work of a single day's food intake (or lack thereof).  This table does not represent the number of people who "went to bed hungry today."
The U.S. Department of Agriculture reported that in 2003, only 1 out of 200 U.S. households with children became so severely food insecure that any of the children went hungry even once during the year. A substantially larger proportion of these same households (3.8 percent) had adult members who were hungry at least one day during the year because of their households' inability to afford enough food.

# Effects
An extended period of malnutrition can result in starvation or deficiency diseases such as scurvy. There may also be a grey discoloration of the nail beds. Malnutrition increases the risk of infection and infectious disease; for example, it is a major risk factor in the onset of active tuberculosis.
Malnutrition appears to increase activity and movement in many animals - for example an experiment on spiders showed increased activity and predation in starved spiders, resulting in larger weight gain. This pattern is seen in many animals, including humans while sleeping. It even occurs in rats with their cerebral cortex or stomachs completely removed. Increased activity on hamster wheels occurred when rats were deprived not only of food, but also water or B vitamins such as thiamine This response may increase the animal's chance of finding food, though it has also been speculated the emigration response relieves pressure on the home population.