Nutrition Diet: How do you interpret MUAC results?

October 20, 2025 •

4 min read

According to the World Health Organization, more than 3 million child deaths annually are linked to malnutrition, emphasizing the critical need for effective screening tools like Mid-Upper Arm Circumference (MUAC). This simple, inexpensive, and non-invasive measurement provides a rapid assessment of an individual's nutritional status by gauging the circumference of the upper arm. Understanding how do you interpret MUAC results is essential for identifying acute malnutrition, particularly in community and emergency settings, allowing for timely intervention and improved health outcomes.

Quick Summary

A MUAC measurement is a quick way to screen for acute malnutrition in children, pregnant women, and adults. Interpreting the results requires using specific cut-offs, often represented by color-coded tapes, that categorize nutritional status from normal to severe acute malnutrition.

Key Points

Screening Tool: MUAC is a fast, simple, and affordable method for screening acute malnutrition, particularly useful in community settings.
Children (6-59 months): MUAC tapes for children are color-coded: green is normal, yellow is moderate acute malnutrition (MAM), and red is severe acute malnutrition (SAM).
Standard Cut-Offs: For children (6-59 months), a MUAC below 11.5 cm indicates SAM, while 11.5 cm to below 12.5 cm indicates MAM.
Pregnant Women: A MUAC below 23 cm in pregnant women is often a marker for undernutrition and increased risk of low birth weight.
Adults: In adults, a MUAC below 23.5 cm may suggest underweight, while over 32 cm could indicate obesity, as it correlates with BMI.
Complementary Measurement: MUAC and Weight-for-Height Z-score often identify different groups of malnourished individuals, so both are used to provide a comprehensive assessment.
Prompt Action: Interpretation of MUAC results should lead to swift action, from supplementary feeding for moderate cases to therapeutic treatment for severe ones.

Mid-Upper Arm Circumference, or MUAC, is a measurement of the upper arm's circumference at its midpoint. It primarily assesses the body's muscle and fat mass, and its effectiveness as a screening tool is due to its simplicity, low cost, and speed. Interpreting MUAC results varies depending on the population, as different cut-off points are used for children, pregnant women, and other adults.

The Measurement Process

To ensure an accurate MUAC reading, follow these steps for proper technique:

Position the person: The person should stand or sit with their left arm bent at a 90-degree angle, with the palm facing up. It is important that the arm is relaxed.
Locate the midpoint: Find the bony point of the shoulder (acromion) and the point of the elbow (olecranon). Measure the distance between these two points with a non-stretchable measuring tape.
Mark the spot: Mark the exact halfway point of that measurement with a pen.
Measure the circumference: Ask the person to let their arm hang loosely at their side. Wrap the tape measure around the arm at the marked midpoint. Ensure the tape is snug against the skin but not so tight that it causes an indentation.
Record the result: Read the measurement and record it in centimeters to the nearest 0.1 cm.

Interpreting MUAC Results in Children (6-59 Months)

For young children, MUAC is a critical tool for identifying acute malnutrition, which is a major contributor to child mortality. A specialized, color-coded tape simplifies the interpretation process, making it accessible even to those with low literacy.

Green Zone: A measurement in the green zone indicates a normal nutritional status. For children aged 6 to 59 months, this typically corresponds to a MUAC of 13.5 cm or greater.
Yellow Zone: A measurement in the yellow zone suggests moderate acute malnutrition (MAM). For children aged 6 to 59 months, this is generally a MUAC between 11.5 cm and 12.5 cm. These children are at risk and require supplementary food, counseling, and regular monitoring to prevent deterioration.
Red Zone: A measurement in the red zone indicates severe acute malnutrition (SAM). A MUAC below 11.5 cm for children aged 6 to 59 months is a common indicator of SAM. This is a life-threatening condition that requires immediate therapeutic feeding and medical care.

Interpreting MUAC in Pregnant Women and Adults

MUAC assessment extends beyond young children to provide a valuable nutritional snapshot for older populations as well. The interpretation varies based on specific physiological and age-related considerations.

Pregnant Women

For pregnant women, particularly in resource-limited settings, MUAC is a reliable and easy-to-use screening tool for identifying malnutrition risk. Low MUAC in pregnancy is significantly linked to adverse outcomes like low birth weight.

At-Risk (Malnutrition): A MUAC below 23 cm is often used as a cut-off point to indicate nutritional risk during pregnancy. Some guidelines may suggest slightly different thresholds based on region or trimester.
Overweight/Obesity: Studies have also explored MUAC in relation to overweight and obesity, with higher MUAC measurements correlating with excessive gestational weight gain. For example, one study suggested a MUAC over 28.0 cm in women of reproductive age could indicate overweight/obesity.

General Adults

In the adult population, MUAC is often used as a proxy for body mass index (BMI), particularly when accurate height measurements are unavailable.

Underweight: A MUAC of less than 23.5 cm may indicate underweight in adults, suggesting a BMI of less than 20 kg/m².
Normal Weight: A MUAC between 23.5 cm and 32 cm is generally associated with a normal BMI.
Overweight/Obesity: A MUAC greater than 32 cm suggests a BMI over 30 kg/m², indicating potential obesity. Some research has proposed higher cut-offs for obesity, such as >31.1 cm, depending on the population.

MUAC vs. Other Nutritional Assessments

While MUAC is a useful screening tool, it is important to understand its role in the context of other nutritional metrics. The table below compares MUAC with the Weight-for-Height Z-score (WHZ), a more complex but often cited diagnostic tool, especially for children.


Feature	Mid-Upper Arm Circumference (MUAC)	Weight-for-Height Z-score (WHZ)
Equipment	Simple, non-stretch tape measure	Requires weighing scales and stadiometers/infantometers
Field-Friendly	Highly portable and easy to use in community settings	Requires more cumbersome equipment, less suitable for rapid screening
Assesses	Acute malnutrition, muscle, and subcutaneous fat	Acute malnutrition (wasting) based on body weight relative to height
Identifies Risk	Strong predictor of mortality risk in children	A specific measure for wasting, but can miss some children identified by MUAC
Use Case	Rapid, community-level screening and admission	Diagnostic tool, often used in clinical settings
Key Insight	Identifies children at highest risk of death	Complements MUAC, but identifies a different subset of children

Management and Follow-Up Based on MUAC

Interpreting MUAC results is only the first step. The next is determining the appropriate course of action based on the identified nutritional status.

Normal (Green Zone): Continue with regular nutritional monitoring, particularly in at-risk populations. Emphasize the importance of a balanced diet and healthy lifestyle.
Moderate Acute Malnutrition (Yellow Zone): Provide supplementary feeding, nutritional counseling, and schedule frequent follow-up visits to monitor progress. The goal is to prevent the condition from worsening.
Severe Acute Malnutrition (Red Zone): Immediate action is necessary. This requires a referral to a therapeutic feeding program or a health facility for specialized medical and nutritional support, often involving ready-to-use therapeutic food (RUTF).

Conclusion

Understanding how do you interpret MUAC results is a vital skill for frontline health workers, caregivers, and public health professionals. It is a simple yet powerful tool for screening malnutrition in children, pregnant women, and adults, enabling the rapid identification of individuals at risk. While MUAC should not replace comprehensive medical diagnosis, its ease of use makes it indispensable for community-level screening, especially in emergencies or resource-constrained environments. By effectively interpreting and acting upon MUAC measurements, it is possible to prevent malnutrition from escalating and to save lives.

For more detailed protocols on MUAC measurements and standards, refer to the WHO guidelines on child growth standards.

Frequently Asked Questions

A normal MUAC reading for a child in this age range is typically 13.5 cm or greater, which corresponds to the green section on a color-coded MUAC tape.

A reading in the red zone (below 11.5 cm) for a child aged 6-59 months indicates severe acute malnutrition, which is a medical emergency. The child requires immediate referral to a health facility for therapeutic feeding and medical care.

MUAC is measured on the left arm at the midpoint between the shoulder's acromion and the elbow's olecranon processes. The tape should be wrapped snugly but not too tightly around the arm.

Yes, MUAC is an effective screening tool for assessing nutritional status in pregnant women. A reading below 23 cm is often used as a cut-off to indicate undernutrition and potential risk of poor birth outcomes.

Yes, in adults, a high MUAC can correlate with overweight or obesity. Some guidelines suggest a MUAC over 32 cm as a marker for a high BMI, though specific cut-offs may vary.

MUAC is a simpler, field-friendly screening tool that identifies children at the highest risk of mortality. WHZ is a more complex diagnostic measure for wasting that may identify a different subset of malnourished children. Both are often used to complement each other.

For a MUAC in the yellow zone (11.5 cm to < 12.5 cm), the child has moderate acute malnutrition. The recommended action includes providing supplementary food, nutritional counseling, and regular monitoring to prevent deterioration into a more severe state.