Health in humanitarian crises  » Hunger and malnutrition »

Acute malnutrition

  • Page updated onMarch 22, 2025
Acute malnutrition
Photo: Bruno Abarca

Acute malnutrition is the result of hunger and the vulnerability it creates. Childhood acute malnutrition weakens the immune system and causes developmental delays. In cases of severe acute malnutrition, there is also an increased risk of death, primarily due to heightened susceptibility to severe cases of acute diarrheal infections, acute respiratory infections, malaria, and measles. Today, it is estimated that severe acute malnutrition accounts for 20% of deaths among children under five, resulting in approximately one million deaths each year.

The scale of the acute malnutrition problem

In 2022, 45 million children under the age of 5 (6.8% of the global population in this age group) suffered from acute malnutrition, with 13.6 million experiencing severe acute malnutrition. The most affected regions include Southeast Asia and Sub-Saharan Africa, especially in areas impacted by humanitarian crises stemming from climate events and conflicts.

Acute malnutrition is closely linked to humanitarian crises. In fact, its measure, global acute malnutrition (GAM), which includes both moderate and severe cases, is often used as an indicator of the severity of an emergency. GAM is considered very low when below 2.5%, low between 2.5% and 5%, moderate between 5% and 10%, high between 10% and 15%, and very high when over 15%. Furthermore, to declare a famine in a given area, among other criteria, GAM prevalence among children under five must exceed 30%. Although there is no official threshold for severe acute malnutrition, many organizations consider a rate above 2% to signal an emergency.

Wasting
UNICEF, WHO and World Bank, 2023

Definition (and diagnosis) of acute malnutrition

Malnutrition and undernutrition

Malnutrition can occur both from deficiency (undernutrition) and excess (obesity and overweight). Although it can affect people of all ages, the term “undernutrition” generally refers to child undernutrition, which includes chronic malnutrition (low height for age), underweight (low weight for age, a general indicator related to both acute and chronic malnutrition), or acute malnutrition.

Acute malnutrition (moderate and severe): the balance between weight and height, and nutritional edema

Acute malnutrition (also known historically as protein-energy malnutrition) encompasses two types of malnutrition: wasting and nutrition-related edema. Although wasting is sometimes equated with acute malnutrition, this is not entirely accurate.

  • On one hand, there is wasting, characterized by a reduction in muscle mass and subcutaneous fat resulting from a caloric deficit. It can be moderate when the weight-for-height or weight-for-length index is low (between 2 and 3 standard deviations below the median of the WHO child growth standard), or severe when it is very low (more than 3 standard deviations below). Severe wasting has historically been known as marasmus.
  • On the other hand, there is nutritional edema, historically known as kwashiorkor, which is swelling caused by fluid retention. This condition presents as bilateral swelling in the feet when the deficiency is primarily protein-based, and it can progressively spread to other parts of the body (including the face). Nutritional edema always corresponds to a case of severe acute malnutrition (never moderate). The pathophysiological mechanisms behind nutritional edema are still not well understood today.

There are, therefore, two levels of acute malnutrition: moderate acute malnutrition (MAM), which always corresponds to moderate wasting; and severe acute malnutrition (SAM), which includes both severe wasting and nutritional edema.

An alternative diagnostic method for acute malnutrition: mid-upper arm circumference (MUAC).

In children aged between 6 months and 5 years, there is another diagnostic criterion that also helps define moderate and severe acute malnutrition: middle-upper arm circumference or MUAC.

The MUAC tape is a simple plastic bracelet about 35cm long that, when placed around a child's arm, allows easy measurement of the child's perimeter. According to its result, it allows to establish whether there is moderate acute malnutrition (between 115mm and 125mm) or severe acute malnutrition (less than 115mm), which is clearly indicated with colors.

The MUAC tape was invented by a British pediatrician in Haiti in 1958 and was first used in 1969 to conduct a population-based screening of nutritional status in Biafra by the ICRC. The use of a cheap, small, portable, and very easy-to-use plastic tape by individuals with minimal training offered numerous advantages over other methods in an extremely chaotic setting. In this context, transporting scales and height boards to measure weight and height—and then cross-referencing the resulting index with growth tables—was unfeasible. Using the MUAC tape allowed the ICRC to identify (and demonstrate) an alarming prevalence of 6.7% severe acute malnutrition.

For years, MUAC was used as a proxy indicator for the weight-for-height index, until scientific evidence showed that this is not entirely accurate. Although they may sometimes yield equivalent results, both diagnostic methods can provide different diagnoses in other cases. Children with a MUAC indicative of acute malnutrition may have a normal weight-for-height index, and vice versa.

Today, both methods are used: weight-for-height and MUAC

Currently, the weight-for-height index is still considered the gold standard for diagnosing acute malnutrition. However, the MUAC is too simple and practical to ignore its results.

The use of MUAC allows for the detection of children at high risk of death in rural and hard-to-reach communities that would otherwise remain unidentified, unreferenced, or untreated. Although the MUAC (and its cutoff points or the ages at which its use is accepted) has a relative arbitrariness, it is a good predictor of child mortality associated with severe acute malnutrition. Therefore, it is widely used in mass screening campaigns during peak risk periods for malnutrition in these areas.

However, specialists recommend avoiding the exclusive use of MUAC in places where the weight-for-height index is also viable (for example, in health centers), due to the risk of leaving children in need of treatment undiagnosed.

Today, MUAC is almost a symbol of the fight against hunger, especially in how it has emerged from the confines of hospitals to reach tiny, under-resourced health posts. It is also a key tool for community health workers and caregivers, who even use MUAC independently to assess whether their children may be malnourished (the Family MUAC approach).

History of the management of acute malnutrition: from the hospital to the community

Initially, acute malnutrition was diagnosed and treated in hospitals

Until almost the end of the 20th century, acute malnutrition could only be treated in hospitals. The reason was justified. The management of child malnutrition required a high availability of beds, facilities, drinking water and specialized personnel in order to implement the ten steps that the guidelines recommended throughout the rehabilitation and stabilization phases.

Clinical protocols were effective. However, in practice, their practical application was virtually impossible in resource-limited contexts. Only 4%-10% of children with acute malnutrition were identified and diagnosed, given the limited access to hospitals. Those few who were diagnosed often presented in an advanced state of severe acute malnutrition. Furthermore, due to their secondary immunodeficiency, hospitalization exposed them to serious co-infections.

As a result, for years, the case fatality rate of hospitalized children with severe acute malnutrition remained at catastrophic levels of 20%-30% for wasting and up to 50%-60% for kwashiorkor.

During the 1970s, attempts were made to develop alternatives for outpatient management

The proposals that emerged during this period were much more economical than the hospital model. However, they did not achieve much better results.

The treatment required the administration of therapeutic milks (F-75 at the beginning and then F-100 in the rehabilitation phase), which was not easy. These products are a combination of powdered milk, sugar, cereal flour, oil, and a mixture of vitamins and minerals. Years later, there would also be a ready-to-use powdered formula. However, its preparation required specialized personnel and clean, drinkable water. Therefore, it had to be administered in community nutritional rehabilitation centers. This posed a significant problem. Having to take the children to these centers daily was an unsustainable burden for the mothers (who were almost always responsible for the care of the children).

In addition to the challenges in increasing coverage, the results in the treated children were also not sustainable. Weight gain was generally low, and often the children experienced severe relapses during treatment or after discharge.

In the 1990s, the RUTF made outpatient management of acute malnutrition feasible

The introduction in 1996 of a new product, Ready-to-Use Therapeutic Food (RUTF), enabled the development of Community Management of Acute Malnutrition (CMAM) since the early 21st century.

Inspired by the cocoa spreads available on the market, scientists created a product made from oil and peanut paste that required no preparation or refrigeration, providing 500 kcal in just 92 g (in a metalized pouch). Additionally, since it contains no water, it is not susceptible to contamination. RUTF was born (along with Plumpy’Nut, the commercial brand of its first and main manufacturer: Nutriset), marking a revolution in the management of acute malnutrition.

The use of RUTF, however, is not without problems. Its use entails a significant increase in the cost of outpatient management of malnutrition. It also offers a lucrative business for its -now- more than 20 manufacturers. In August 2024, the price for the approximate number of RUTF pouches needed for a child with severe acute malnutrition during treatment (150 units) is priced at 62.60 USD in the catalog of the UNICEF Supply Division (which supplies around 80% of the global demand for this product).

In any case, RUTF, despite its cost, has proven to be the only real therapeutic option for the community management of malnutrition. Fortunately, its cost remains much lower (not only economically but primarily in human terms) than what hospital management would entail today.

Related blog articles:

Management and treatment of acute malnutrition today

Once a child with acute malnutrition is diagnosed with MUAC or weight-for-height index in the community or a health center, they must be classified as infants (children under 6 months) at risk of poor growth and development, children under 5 years with moderate acute malnutrition, or children under 5 years with severe acute malnutrition.

Management of children under 6 months of age at risk of acute malnutrition

The current approach recognizes the interdependence in the mother-child dyad for their survival and well-being. Therefore, in managing infants under 6 months at risk, the main objective is to detect any medical or psychological issues that could trigger severe acute malnutrition, while also supporting caregivers (especially mothers) in their health.

The danger signs to be identified include severe acute health problems, recent weight loss, nutritional edema, medical issues that require a thorough clinical assessment, breastfeeding problems (making it ineffective), issues when using breast milk substitutes (for example, if there are concerns about inappropriate or unsafe use), or a diagnostic anthropometric value of acute malnutrition (weight-for-age or weight-for-length below 2 standard deviations, or MUAC below 110mm). In these cases, they should receive hospital care, although they may return to outpatient care as they begin to improve.

When these children are only at risk, they should receive assistance with breastfeeding, supplementation, and maternal support interventions, including mental health care, depending on the situation.

Management of moderate acute malnutrition in children 6 months to 5 years of age

When there is moderate acute malnutrition in this age group, a nutrient-dense diet is recommended, with elements available in the local market or provided through humanitarian assistance, along with a psychosocial evaluation and assessment of other concurrent health issues. In higher-risk cases, the use of specially formulated lipid-based supplements (such as Ready-to-Use Supplementary Food or RUSF, and even RUTF), solid-based supplements (such as BP-100 biscuits), or fortified mixes with added sugar, oil, and/or milk is recommended.

Management of severe acute malnutrition in children from 6 months to 5 years of age

Finally, when there is severe acute malnutrition in these age groups, treatment with 150-185 kcal/kg/day of RUTF is recommended until recovery (or with a reduction in the amount when nutritional edema resolves or emaciation becomes moderate).

In some rare cases, danger signals are detected, such as very severe edema, acute medical problems (or those requiring in-depth evaluation), lack of appetite, or failure to gain weight with normal treatment. When this occurs, inpatient treatment is recommended, although they may be referred to outpatient treatment as they improve.

How to reach and treat all acutely malnourished children?

CMAM coverage
Action Against Hunger. The state of acute malnutrition.

Coverage of management of childhood acute malnutrition remains a major challenge

Today, thanks to the MUAC, the RUTF, and the efforts of so many professionals and community health and nutrition workers, the treatment of acute malnutrition is mainly carried out on an outpatient basis. As a result, coverage has increased. However, it is still very insufficient. Although assessing access to treatment coverage is difficult (it requires studies such as SQUEAC surveys) and is done less frequently than desired, it is estimated that 2 out of 3 children with severe acute malnutrition do not have access to the treatment they need.

The main barriers? The distances to travel to receive health care (even if it is at a health post or center rather than a hospital), weaknesses in mobile and community outreach health services, lack of information or awareness of the problem of acute malnutrition, and problems in the provision and supply of RUTF, which many governments still do not cover.

Innovations in the management of childhood acute malnutrition for increased coverage

Numerous innovations are being researched and implemented to evolve the management of acute malnutrition towards a model better suited for community approaches. Among these potential innovations are:

  • The simplification and integration of protocols for managing moderate and severe acute malnutrition into a single protocol. This allows personnel to achieve equal or more effective performance with less training and supervision.
  • The combination of using MUAC with a weight-for-age index that allows for better diagnosis (without requiring the transport of a height measuring device).
  • The reduction in RUTF doses. This would allow for a decrease in its usage costs and increase its availability for more patients.
  • The use of digital tools for the diagnosis and management of malnutrition.
  • The inclusion of the management of uncomplicated moderate and severe acute malnutrition among the tasks of community health workers.

So far, the most promising approach appears to be the incorporation of acute malnutrition management into the activity package of community health workers. These volunteers already diagnosed and treated common childhood illnesses such as acute diarrhea, respiratory infections, or malaria, as well as conducted health education and promotion activities. Recent research by Action Against Hunger shows that these programs achieve similar performance and recovery rates to management by nursing staff in health centers, with lower costs and greater coverage. In 2023, the WHO included this as a recommendation in its new guidelines, always on the condition that these volunteers are integrated as health personnel within the health system with proper training and supervision.

Hunger and malnutrition

External links

en_USEnglish
es_ESEspañol en_USEnglish
Scroll to Top