Other namesMalnourishment
Orange ribbon.svg
An orange ribbon – the awareness ribbon for malnutrition.
SpecialtyCritical care medicine
SymptomsProblems with physical or mental development, poor energy levels, hair loss, swollen legs and abdomen[1][2]
CausesEating a diet in which nutrients are either not enough or are too much, malabsorption[3][4]
Risk factorsNot breastfeed, gastroenteritis, pneumonia, malaria, measles[5]
PreventionImproving agricultural practices, reducing poverty, improving sanitation, empowerment of women[6][7]
TreatmentImproved nutrition, supplementation, ready-to-use therapeutic foods, treating the underlying cause[6][8][9]
Frequency821 million undernourished / 11% of the population (2017)[10]
Deaths406,000 from nutritional deficiencies (2015)[11]

Malnutrition is a condition that results from eating a diet in which one or more nutrients are either not enough or are too much such that the diet causes health problems.[1][3] It may involve calories, protein, carbohydrates, vitamins or minerals.[1] Not enough nutrients is called undernutrition or undernourishment while too much is called overnutrition.[2] Malnutrition is often used to specifically refer to undernutrition where an individual is not getting enough calories, protein, or micronutrients.[2][12] If undernutrition occurs during pregnancy, or before two years of age, it may result in permanent problems with physical and mental development.[1] Extreme undernourishment, known as starvation, may have symptoms that include: a short height, thin body, very poor energy levels, and swollen legs and abdomen.[1][2] People also often get infections and are frequently cold.[2] The symptoms of micronutrient deficiencies depend on the micronutrient that is lacking.[2]

Undernourishment is most often due to not enough high-quality food being available to eat.[5] This is often related to high food prices and poverty.[1][5] A lack of breastfeeding may contribute, as may a number of infectious diseases such as: gastroenteritis, pneumonia, malaria, and measles, which increase nutrient requirements.[5] There are two main types of undernutrition: protein-energy malnutrition and dietary deficiencies.[12] Protein-energy malnutrition has two severe forms: marasmus (a lack of protein and calories) and kwashiorkor (a lack of just protein).[2] Common micronutrient deficiencies include: a lack of iron, iodine, and vitamin A.[2] During pregnancy, due to the body's increased need, deficiencies may become more common.[13] In some developing countries, overnutrition in the form of obesity is beginning to present within the same communities as undernutrition.[14] Other causes of malnutrition include anorexia nervosa and bariatric surgery.[15][16]

Efforts to improve nutrition are some of the most effective forms of development aid.[6] Breastfeeding can reduce rates of malnutrition and death in children,[1] and efforts to promote the practice increase the rates of breastfeeding.[8] In young children, providing food (in addition to breastmilk) between six months and two years of age improves outcomes.[8] There is also good evidence supporting the supplementation of a number of micronutrients to women during pregnancy and among young children in the developing world.[8] To get food to people who need it most, both delivering food and providing money so people can buy food within local markets are effective.[6][17] Simply feeding students at school is insufficient.[6] Management of severe malnutrition within the person's home with ready-to-use therapeutic foods is possible much of the time.[8] In those who have severe malnutrition complicated by other health problems, treatment in a hospital setting is recommended.[8] This often involves managing low blood sugar and body temperature, addressing dehydration, and gradual feeding.[8][18] Routine antibiotics are usually recommended due to the high risk of infection.[18] Longer-term measures include: improving agricultural practices,[7] reducing poverty, improving sanitation, and the empowerment of women.[6]

There were 821 million undernourished people in the world in 2018 (10.8% of the total population).[19] This is a reduction of about 176 million people since 1990 when 23% were undernourished, but an increase of about 36 million since 2015, when 10.6% were undernourished.[10][20] In 2012, it was estimated that another billion people had a lack of vitamins and minerals.[6] In 2015, protein-energy malnutrition was estimated to have resulted in 323,000 deaths—down from 510,000 deaths in 1990.[11][21] Other nutritional deficiencies, which include iodine deficiency and iron deficiency anemia, result in another 83,000 deaths.[11] In 2010, malnutrition was the cause of 1.4% of all disability adjusted life years.[6][22] About a third of deaths in children are believed to be due to undernutrition, although the deaths are rarely labelled as such.[5] In 2010, it was estimated to have contributed to about 1.5 million deaths in women and children,[23] though some estimate the number may be greater than 3 million.[8] An additional 165 million children were estimated to have stunted growth from malnutrition in 2013.[8] Undernutrition is more common in developing countries.[24] Certain groups have higher rates of undernutrition, including women—in particular while pregnant or breastfeeding—children under five years of age, and the elderly. In the elderly, undernutrition becomes more common due to physical, psychological, and social factors.[25]


Child in the United States with signs of Kwashiorkor, a dietary protein deficiency.

Unless specifically mentioned otherwise, the term malnutrition refers to undernutrition for the remainder of this article. Malnutrition can be divided into two different types, SAM and MAM. SAM refers to children with severe acute malnutrition. MAM refers to moderate acute malnutrition.[26]

Undernutrition and overnutrition

Malnutrition is caused by eating a diet in which nutrients are not enough or is too much such that it causes health problems.[27] It is a category of diseases that includes undernutrition and overnutrition.[28] Overnutrition can result in obesity and being overweight. In some developing countries, overnutrition in the form of obesity is beginning to present within the same communities as undernutrition.[29]

However, the term malnutrition is commonly used to refer to undernutrition only.[30] This applies particularly to the context of development cooperation. Therefore, "malnutrition" in documents by the World Health Organization, UNICEF, Save the Children or other international non-governmental organizations (NGOs) usually is equated to undernutrition.

Protein-energy malnutrition

Undernutrition is sometimes used as a synonym of protein–energy malnutrition (PEM).[2] While other include both micronutrient deficiencies and protein energy malnutrition in its definition.[12] It differs from calorie restriction in that calorie restriction may not result in negative health effects. The term hypoalimentation means underfeeding.[31]

The term "severe malnutrition" or "severe undernutrition" is often used to refer specifically to PEM.[32] PEM is often associated with micronutrient deficiency.[32] Two forms of PEM are kwashiorkor and marasmus, and they commonly coexist.[27]


Kwashiorkor is mainly caused by inadequate protein intake.[27] The main symptoms are edema, wasting, liver enlargement, hypoalbuminaemia, steatosis, and possibly depigmentation of skin and hair.[27] Kwashiorkor is further identified by swelling of the belly, which is deceiving of actual nutritional status.[33] The term means ‘displaced child’ and is derived from a Ghana language of West Africa, means "the sickness the older one gets when the next baby is born," as this is when the older child is deprived of breast feeding and weaned to a diet composed largely of carbohydrates.[34]


Marasmus (‘to waste away’) is caused by an inadequate intake of protein and energy. The main symptoms are severe wasting, leaving little or no edema, minimal subcutaneous fat, severe muscle wasting, and non-normal serum albumin levels.[27] Marasmus can result from a sustained diet of inadequate energy and protein, and the metabolism adapts to prolong survival.[27] It is traditionally seen in famine, significant food restriction, or more severe cases of anorexia.[27] Conditions are characterized by extreme wasting of the muscles and a gaunt expression.[33]

Undernutrition, hunger

Undernutrition encompasses stunted growth (stunting), wasting, and deficiencies of essential vitamins and minerals (collectively referred to as micronutrients). The term hunger, which describes a feeling of discomfort from not eating, has been used to describe undernutrition, especially in reference to food insecurity.[35]

Definition by Gomez

In 1956, Gómez and Galvan studied factors associated with death in a group of malnourished (undernourished) children in a hospital in Mexico City, Mexico and defined categories of malnutrition: first, second, and third degree.[36] The degrees were based on weight below a specified percentage of median weight for age.[37] The risk of death increases with increasing degree of malnutrition.[36] An adaptation of Gomez's original classification is still used today. While it provides a way to compare malnutrition within and between populations, the classification has been criticized for being "arbitrary" and for not considering overweight as a form of malnutrition. Also, height alone may not be the best indicator of malnutrition; children who are born prematurely may be considered short for their age even if they have good nutrition.[38]

Degree of PEM % of desired body weight for age and sex
Normal 90–100%
Mild: Grade I (1st degree) 75–89%
Moderate: Grade II (2nd degree) 60–74%
Severe: Grade III (3rd degree) <60%
SOURCE:"Serum Total Protein and Albumin Levels in Different Grades of Protein Energy Malnutrition"[33]

Definition by Waterlow

John Conrad Waterlow established a new classification for malnutrition.[39] Instead of using just weight for age measurements, the classification established by Waterlow combines weight-for-height (indicating acute episodes of malnutrition) with height-for-age to show the stunting that results from chronic malnutrition.[40] One advantage of the Waterlow classification over the Gomez classification is that weight for height can be examined even if ages are not known.[39]

Degree of PEM Stunting (%) Height for age Wasting (%) Weight for height
Normal: Grade 0 >95% >90%
Mild: Grade I 87.5–95% 80–90%
Moderate: Grade II 80–87.5% 70–80%
Severe: Grade III <80% <70%
SOURCE: "Classification and definition of protein-calorie malnutrition." by Waterlow, 1972[39]

These classifications of malnutrition are commonly used with some modifications by WHO.[37]

Other Languages
Alemannisch: Mangelernährung
العربية: سوء التغذية
aragonés: Malnutrición
অসমীয়া: অপুষ্টি
asturianu: Malnutrición
বাংলা: অপুষ্টি
Bân-lâm-gú: Êng-ióng-put-liông
башҡортса: Ашау етмәү
беларуская: Недаяданне
беларуская (тарашкевіца)‎: Недаяданьне
български: Недохранване
bosanski: Neuhranjenost
буряад: Үлдэлгэ
català: Malnutrició
čeština: Malnutrice
Cymraeg: Diffyg maeth
डोटेली: कुपोषण
Ελληνικά: Δυσθρεψία
español: Malnutrición
euskara: Malnutrizio
فارسی: سوءتغذیه
français: Malnutrition
Gaeilge: Míchothú
ગુજરાતી: કુપોષણ
한국어: 영양실조
հայերեն: Թերսնուցում
हिन्दी: कुपोषण
hrvatski: Malnutricija
Igbo: Agụụ
Bahasa Indonesia: Malagizi
isiXhosa: Ukungondleki
isiZulu: Ukungondleki
íslenska: Næringarkvilli
italiano: Malnutrizione
עברית: תת-תזונה
қазақша: Аштық
Kiswahili: Utapiamlo
kurdî: Bedxwerî
lietuvių: Neprievalgis
Limburgs: Malnutritie
lingála: Bolei Mabe
македонски: Неисхранетост
मराठी: कुपोषण
Bahasa Melayu: Malnutrisi
Mìng-dĕ̤ng-ngṳ̄: Bâng-găng
Nederlands: Malnutritie
नेपाली: कुपोषण
नेपाल भाषा: कुपोषण
日本語: 栄養失調
occitan: Malnutricion
ଓଡ଼ିଆ: କୁପୋଷଣ
oʻzbekcha/ўзбекча: Och qolish
ਪੰਜਾਬੀ: ਕੁਪੋਸ਼ਣ
پنجابی: کمزوری
português: Desnutrição
română: Malnutriție
русский: Недоедание
संस्कृतम्: कुपोषणम्
Sesotho sa Leboa: Phepompe
Simple English: Malnutrition
slovenčina: Malnutrícia
slovenščina: Podhranjenost
Soomaaliga: Nafaaqodarro
کوردی: بەدخۆراکی
српски / srpski: Неухрањеност
srpskohrvatski / српскохрватски: Neishranjenost
svenska: Näringsbrist
Tagalog: Malnutrisyon
татарча/tatarça: Ачлы-туклы яшәү
Türkçe: Malnütrisyon
українська: Недоїдання
Tiếng Việt: Kém dinh dưỡng
Winaray: Malnutrisyon
Wolof: Xiibon
吴语: 营养弗良
粵語: 唔夠營養
中文: 營養不良