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Acute malnutrition (wasting): MUAC, RUTF and community care

  • Page updated onJuly 6, 2026
A community health worker measures a child's mid-upper arm circumference (MUAC) during acute malnutrition screening in Mauritania
Text and 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 2024, 42.8 million children under 5 (6.6% of the global population of that age group) suffered from acute malnutrition, of whom 12.2 million suffered from severe acute malnutrition. The most affected regions are South-East Asia and sub-Saharan Africa, and especially areas affected by humanitarian crises resulting from climate events and conflicts (UNICEF et al., 2025).

Acute malnutrition is closely linked to humanitarian crises (FAO et al., 2025). In fact, its measure, global acute malnutrition (GAM), which includes both moderate and severe forms, is often used as an indicator of the magnitude of the emergency. It is considered very low when below 2.5%, low when between 2.5% and 5%, medium when between 5% and 10%, high when between 10% and 15%, and very high when above 15%. Moreover, to determine a famine situation in an area, among other conditions, the prevalence of global acute malnutrition in children under 5 must exceed 30%. Although there is no official threshold for severe acute malnutrition, many organisations consider 2% to be an emergency level.

Joint Malnutrition Estimates
UNICEF, WHO and the World Bank, 2025

What is acute malnutrition? Definition and diagnostic criteria

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.

Types of acute malnutrition

Acute malnutrition (historically referred to as protein-energy malnutrition) encompasses two types of malnutrition: wasting and nutrition-related oedema (Bhutta et al., 2017). Although wasting is sometimes equated with acute malnutrition, this is not entirely accurate.

  • On one hand there is wasting, characterised by the reduction of muscle mass and subcutaneous fat resulting from a caloric deficit, which 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 standards), or severe when it is very low (below 3 standard deviations) (Save the Children, 2015). 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 allows the definition of moderate and severe acute malnutrition: mid-upper arm circumference (MUAC) (Buttarelli et al., 2021).

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.

MUAC was invented by a British paediatrician in Haiti in 1958 and was first used in 1969 for a population-level nutritional screening in Biafra by the ICRC. The use of a plastic tape measure — cheap, small, easy to transport and very easy to use by people with minimal training — offered numerous advantages over the alternative in an enormously chaotic environment. In this context it was not feasible to transport scales and stadiometers to measure weight and height and then cross-reference the resulting index with reference tables. The use of MUAC allowed the ICRC to find (and demonstrate) an alarming prevalence of 6.7% of severe acute malnutrition (Glasman, 2018).

For years, mid-upper arm circumference was used as a proxy indicator for weight-for-height, until scientific evidence showed that this is not entirely accurate. Although the two methods can sometimes yield equivalent results, in other cases both diagnostic methods produce different diagnoses. Children with a MUAC indicative of acute malnutrition may have a normal weight-for-height, and vice versa (Grellety & Golden, 2016).

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 hospital to community

Initially, acute malnutrition was diagnosed and treated in hospitals

Until practically the end of the twentieth century, the treatment of acute malnutrition could only be carried out in hospitals. The reason was justified. The management of childhood malnutrition required a high availability of beds, resources, safe drinking water and specialist staff in order to implement the ten steps recommended by the guidelines throughout the stabilisation and rehabilitation phases (Ashworth et al., 2003).

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 hospitalised children with severe acute malnutrition remained at catastrophic levels of 20%–30% for marasmus and up to 50%–60% for kwashiorkor (Schofield & Ashworth, 1996).

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

The proposals that emerged during this period were far less costly than the hospital model. However, they also failed to achieve significantly better results (Ashworth et al., 2003).

Treatment required the administration of therapeutic milks (F-75 initially and then F-100 during the rehabilitation phase), which was not straightforward (Collins et al., 2006). These products are a combination of powdered milk, sugar, cereal flour, oil and a mix of vitamins and minerals. Years later, a ready-to-use powdered formula would also become available. However, their preparation required specialist staff and clean, safe drinking water. For this reason, they had to be administered at community nutritional rehabilitation centres. This posed a major problem. Having to bring children to these centres daily was an unsustainable burden for mothers (who were responsible for childcare in almost all cases) (Briend et al., 1999).

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 the late 1990s of a new product, Ready-to-Use Therapeutic Food (RUTF), was what enabled the development of Community Management of Acute Malnutrition (CMAM) from the early twenty-first century onwards (Briend et al., 1999).

Drawing inspiration from chocolate spread products available on the market, scientists created a product made from oil and peanut paste that required no preparation or refrigeration, providing 500kcal in just 92g (in a foil sachet). Moreover, as it contains no water, it is not susceptible to contamination. RUTF had been born (and with it Plumpy'Nut, the brand name of its first and main manufacturer, Nutriset), and with it a revolution in the management of acute malnutrition (Briend & Collins, 2010).

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 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 viable therapeutic option for the community management of malnutrition. Fortunately, its cost also remains far lower — not only in economic terms but above all in human terms — than hospital-based management would entail today (Collins et al., 2006).

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The management and treatment of acute malnutrition today, from infants to adolescents

Once a child with acute malnutrition is diagnosed using MUAC or the weight-for-height index in the community or a health facility, they must be classified as: infants (children under 6 months) at risk of growth and developmental delay, children under 5 with moderate acute malnutrition, or children under 5 with severe acute malnutrition (WHO, 2023).

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

The current approach recognises the interdependence in the mother-child dyad for their survival and wellbeing. For this reason, in the management of at-risk infants under 6 months, the main objective is to detect any medical or psychological problems that could trigger severe acute malnutrition, while simultaneously supporting caregivers (especially mothers) in their own health (MAMI Global Network et al., 2021).

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.

Management of severe acute malnutrition in children and adolescents aged 5 to 19 years

Acute malnutrition in school-age children (over 5 years of age) and adolescents up to 19 years of age, has generally remained in the background in clinical guidelines and protocols, as it is less prevalent. However, it does occur in emergency contexts with high levels of food and nutrition insecurity, especially in contexts of conflict and siege.

In late 2025, the Global Nutrition Cluster published a brief technical guide with recommendations for adapting the diagnostic, treatment and medical and nutritional follow-up criteria to this age group (Global Nutrition Cluster, 2025b). The recommended diagnostic criteria include any of the following: MUAC-for-age, weight-for-age, BMI-for-age and the presence of bilateral oedema. Regarding treatment, the main difference lies in the age-based simplified dosage adjustment, modifying the number of daily RUTF sachets according to the age groups of 5–9 years, 10–13 years and 14–19 years. Attention must also be paid to other issues, such as vitamin A over-supplementation and its potential teratogenicity in adolescent pregnancies.

Coverage and innovations in the community-based management of acute malnutrition

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

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If we have the technical knowledge to diagnose and treat acute malnutrition in primary and outpatient health centers, why does it continue to be a major cause of child mortality? Is it only due to a lack of means and resources?

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Coverage of management of childhood acute malnutrition remains a major challenge

Today, thanks to MUAC, RUTF and the efforts of so many health and nutrition professionals and community health workers, the treatment of acute malnutrition is carried out primarily on an outpatient basis. As a result, coverage has increased. However, it remains very insufficient (Rogers et al., 2015). Although evaluating treatment coverage is difficult (requiring studies such as SQUEAC surveys) and is carried out less frequently than would be desirable, it is estimated that 2 out of every 3 children with severe acute malnutrition do not have access to the treatment they need.

What are the main barriers? The distances that must be covered to receive healthcare (even at a health post or centre rather than a hospital), weaknesses in mobile and community outreach health services, a lack of information or awareness about the problem of acute malnutrition, and supply and procurement problems with RUTF, which many governments still do not cover (Global Nutrition Cluster, 2025a). Addressing all of these problems requires coordinated action among multiple actors (FAO et al., 2020).

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 even better adapted to its treatment in the community (Action Against Hunger, 2021). These possible innovations include:

  • 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.

To date, the most promising appears to be the incorporation of acute malnutrition management into the package of activities of community health workers (Action Against Hunger, 2024). These volunteers were already carrying out diagnosis and treatment of common childhood illnesses such as acute diarrhoea, respiratory infections and malaria, as well as health education and promotion activities. Recent research by Action Against Hunger shows that these programmes achieve performance and cure rates similar to those of nursing staff in health facilities, at lower cost and with greater coverage. In 2023, the WHO included it as a recommendation in its new guidelines, provided that these volunteers are integrated as health workers into the health system with adequate training and supervision (WHO, 2023).

References

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How to cite this page

Abarca, B. (July 6, 2026). Acute malnutrition (wasting): MUAC, RUTF and community care. Salud Everywhere. https://saludeverywhere.com/en/health-in-humanitarian-crises/acute-malnutrition/

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