Malnutrition is the condition that results from eating a diet in which certain nutrients are lacking, in excess (too high an intake), or in the wrong proportions. The verb form is "malnourish"; "malnourishment" is sometimes used instead of "malnutrition". A number of different nutrition disorders may arise, depending on which nutrients are under- or over-abundant in the diet. In most of the world, malnutrition is present in the form of under-nutrition, which is caused by a diet lacking adequate calories and protein—not enough food, and of poor quality. Extreme undernourishment is starvation, and its symptoms and effects are inanition. While malnutrition is more common in less-developed countries, it is also present in industrialized countries. In wealthier nations it is more likely to be caused by unhealthy diets with excess energy, fats, and refined carbohydrates. A growing trend of obesity is now a major public health concern in lower socio-economic levels and in developing countries as well.
The World Health Organization cites malnutrition as the greatest single threat to the world's public health. Improving nutrition is widely regarded as the most effective form of aid. Nutrition-specific interventions, which address the immediate causes of undernutrition, have been proven to deliver among the best value for money of all development interventions. Emergency measures include providing deficient micronutrients through fortified sachet powders or directly through supplements. WHO, UNICEF, and the UN World Food Programme recommend community management of severe acute malnutrition with ready-to-use therapeutic foods, which have been shown to cause weight gain in emergency settings. The famine relief model increasingly used by aid groups calls for giving cash or cash vouchers to the hungry to pay local farmers instead of buying food from donor countries, often required by law, to prevent dumping from hurting local farmers.
Long term measures include fostering nutritionally dense agriculture by increasing yields, while making sure negative consequences affecting yields in the future are minimized. Recent efforts include aid to farmers. However, World Bank strictures restrict government subsidies for farmers, while the spread of fertilizer use may adversely affect ecosystems and human health and is hampered by various civil society groups.
Malnutrition has shown to be an important concern in women, children, and the elderly. Because of pregnancies and breastfeeding, women have additional nutrient requirements. Children can be at risk for malnutrition even before birth, as their nutrition levels are directly tied to the nutrition of their mothers. Breastfeeding can reduce rates of malnutrition and mortality in children, and educational programs for mothers could have a large impact on these rates. The elderly have a large risk of malnutrition because of unique complications such as changes in appetite and energy level, and chewing and swallowing problems. Adequate elderly care is essential for preventing malnutrition, especially when the elderly cannot care for themselves.