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Most care professionals know malnutrition is a serious risk for older adults at home. What's less obvious is when to act on it - and what to do when standard measurements aren't possible.
That's where the Malnutrition Universal Screening Tool (MUST) comes in. It's a standardised, evidence-based framework that helps care teams identify malnutrition risk early, before it leads to hospitalisation, slower recovery, or worsening health outcomes.
This guide explains what the MUST score is, how it works in practice, what to do when measurements are challenging, and how to respond appropriately to each risk level.
What is the MUST score?
The MUST score is a five-step screening tool developed by the British Association for Parenteral and Enteral Nutrition (BAPEN). It's designed to identify adults at risk of malnutrition in any care setting - including domiciliary care, where 93% of people at risk of malnutrition live.
The tool categorises individuals into three risk levels:
- 0 = Low risk
- 1 = Medium risk
- 2+ = High risk
Each risk level triggers a different care response, from routine monitoring to referral to a dietitian or GP.
Unlike subjective observation alone, MUST provides a consistent, repeatable method for assessing nutritional risk across your service. It combines objective measurements (where possible) with clinical judgement to ensure everyone receives an appropriate assessment, even when conditions aren't ideal.
The three components of the MUST score
MUST calculates risk using three factors:
1. Body Mass Index (BMI)
BMI indicates whether someone is underweight for their height. It's calculated as:
Weight (kg) ÷ Height (m)²
- BMI >20 = 0 points
- BMI 18.5–20 = 1 point
- BMI <18.5 = 2 points
2. Unintentional weight loss
Weight loss over the past 3–6 months is one of the earliest signs of malnutrition.
- <5% weight loss = 0 points
- 5–10% weight loss = 1 point
- >10% weight loss = 2 points
This is why regular weight tracking matters. Without a baseline, you can't identify change.
3. Acute disease effect
If the person is acutely unwell and has had little or no nutritional intake for more than 5 days, add 2 points.
This factor captures situations where someone is at immediate risk—such as after a hospital discharge, during illness, or following a fall.
How to calculate the MUST score: a step-by-step guide
- Measure height and weight accurately. Use calibrated scales and, where possible, measure height rather than relying on self-reported data.
- Calculate BMI and assign the corresponding score (0, 1, or 2).
- Assess weight loss over the past 3–6 months and assign a score.
- Consider acute disease effect. If the person has been acutely unwell with minimal intake for >5 days, add 2 points.
- Add the three scores together to get the total MUST score.
- Use the score to determine the appropriate management plan (detailed below).
BAPEN provides a detailed MUST guidance booklet with charts and further interpretation notes.
What to do when measurements aren't possible
In domiciliary care, you won't always be able to measure height and weight accurately. Someone may be bedbound, unable to stand safely, or using equipment like a wheelchair that makes standard measurements impractical.
When this happens, you have alternatives:
Estimating height from ulna length
If you can't measure standing height, you can estimate it using the ulna bone (the forearm bone running from elbow to wrist).
How to do it:
- Ask the person to bend their left arm across their chest, with fingers pointing toward the opposite shoulder
- Using a flexible tape measure, measure from the tip of the elbow (olecranon) to the prominent bone at the wrist (styloid process)
- Record the measurement in centimetres to the nearest 0.5 cm
- Use standard NHS conversion charts to estimate height based on ulna length, sex, and age
This method provides a reliable proxy when direct height measurement isn't feasible.
Using Mid Upper Arm Circumference (MUAC) to estimate BMI
If you can't obtain accurate height or weight measurements, MUAC offers a quick alternative indicator of nutritional status.
How to measure MUAC:
- Ask the person to bend their left arm at a right angle (90 degrees)
- Find the midpoint between the top of the shoulder and the tip of the elbow
- Measure around the arm at this point with a soft tape measure
What the measurements suggest:
- MUAC <23.5 cm suggests BMI <20 kg/m² (potential undernutrition risk)
- MUAC >32 cm suggests BMI >30 kg/m² (obesity)
Important note: MUAC is an estimation tool, not a replacement for calculating a full MUST score. It's most useful for flagging potential risk when standard measurements aren't possible.
Using subjective criteria when measurements aren't available
When neither objective measurements nor alternative methods are practical, use clinical observation and subjective assessment:
- Visual assessment: Does the person appear very thin with visible muscle wasting? Or overweight?
- Clothing changes: Have clothes, belts, or rings become noticeably looser, suggesting unplanned weight loss?
- Self-reported changes: Has the person or their family noticed reduced appetite, decreased food intake, or difficulty swallowing?
- Functional changes: Has there been a decline in ability to prepare meals or feed themselves?
- Recent illness: Has the person been acutely unwell with minimal intake for 5+ days?
While subjective criteria are less precise than measurements, they allow you to make an informed judgement about nutritional risk and ensure no one falls through the gaps.
What to do based on MUST score: risk-specific actions
A MUST score on its own doesn't improve outcomes. The value comes from acting on it appropriately.
Low risk (MUST score = 0)
What this means: The person is not currently at significant risk of malnutrition.
What to do:
- Continue with routine care and standard clinical practices
- Provide practical advice on balanced diet choices and hydration as needed
- Repeat screening:
- In hospital: weekly
- In care homes: monthly
- In the community: annually (or whenever circumstances change)
Document the risk category and any specific dietary needs in care notes
Special consideration for obesity: If obesity is present, record it in the care plan. Underlying health conditions (such as diabetes or cardiovascular disease) should typically be addressed before focusing on weight management. Coordinate any weight-related interventions with the person's GP.
Medium risk (MUST score = 1)
What this means: The person shows early signs of nutritional risk and needs closer monitoring.
What to do:
- Observe and document food and fluid intake for 3 days
- If intake is adequate:
- Continue regular screening (weekly in hospital, monthly in care homes, every 2–3 months in community settings)
- Monitor for any changes in appetite, weight, or health status
- If intake is inadequate or there are clinical concerns:
- Follow local policies for nutritional intervention
- Set clear goals to improve nutritional intake
- Consider whether additional support is needed (e.g., assistance with meals, fortified foods)
- Repeat MUST screening monthly
- Refer to a dietitian if no improvement after intervention
- Document all observations and actions in the care plan
High risk (MUST score = 2+)
What this means: The person is at significant risk of malnutrition and requires immediate intervention.
What to do:
- Refer to a dietitian, nutritional support team, or GP immediately (unless nutritional support would be detrimental or offers no benefit, such as in end-of-life care)
- Implement a nutritional support plan with specific, measurable goals
- Monitor and review frequently:
- In hospital: weekly
- In the community/care homes: monthly
- Work to improve and increase overall nutritional intake through:
- Meal fortification (adding calories and protein to existing meals)
- Nutritional supplements if recommended by healthcare professionals
- Addressing any barriers to eating (pain, swallowing difficulties, poor dentition, low mood)
- Providing assistance with eating and drinking if needed
- Document all interventions, goals, and progress clearly
- Communicate the person's risk status to all relevant team members, family, and healthcare professionals
For all risk levels:
- Treat any underlying conditions contributing to malnutrition (infection, medication side effects, pain, depression)
- Offer practical help and advice on food choices, eating, and drinking
- Record the malnutrition risk category and communicate it clearly across the care team
- Document any special dietary needs and follow local protocols
- Reassess whenever the person moves between care settings (hospital to home, between services, or into a care home) to ensure continuity of nutritional support
Why reassessment matters when care settings change
Nutritional needs don't stay static. They can shift rapidly due to changes in health status, medical treatments, or care environment.
A person recently discharged from hospital may have new dietary requirements or be more vulnerable to malnutrition during recovery. Someone moving into a care home may experience disruptions to appetite or access to preferred meals.
By reassessing MUST scores whenever someone transitions between care settings, you can:
- Spot new or escalating nutritional challenges quickly
- Adjust care plans promptly to reflect current needs
- Prevent malnutrition risk from going unnoticed during periods of change
- Maintain continuity of care and communication between services
This is particularly important in domiciliary care, where people may move between hospital, home, rehabilitation facilities, and respite care—each with different routines, meal provision, and support structures.
How technology supports MUST screening and nutrition monitoring
Screening only works if it's integrated into your daily workflow - not treated as an isolated task. Modern care platforms like Birdie make it easier to:
- Track weight and BMI over time, so you can spot trends early and calculate percentage weight loss accurately
- Record food and fluid intake systematically during every visit, rather than relying on memory
- Document MUST assessments as part of structured clinical observations
- Set alerts for changes in appetite, weight, or wellbeing, so managers can respond quickly
- Share nutrition data with families via the Family app, keeping them informed and involved
- Generate reports for audits and care reviews, demonstrating your approach to malnutrition risk management across your service
Birdie supports MUST assessments as part of its clinical observation features, helping care teams move from reactive to proactive nutrition care.
This method provides a reliable proxy when direct height measurement isn't feasible.
Common challenges (and how to address them)
"We don't have time to weigh people regularly."
If weight tracking feels like an added task, it's a sign it's not embedded in your care planning. Regular weighing should be part of routine visits for anyone with nutritional risk factors - and documented in the care plan as a standard activity, not an optional extra.
"We complete the MUST but don't know what to do with the score."
A score on its own doesn't improve outcomes. The value comes from acting on it: adjusting meal support, involving a dietitian, or monitoring more closely. Make sure your care plans specify the next steps for each risk level, and that all staff understand what action each score requires.
"We can't measure height and weight for some of our clients."
Use alternative methods: ulna length to estimate height, MUAC to estimate BMI category, or subjective clinical observations. The goal is to assess nutritional risk as accurately as possible given the circumstances - not to achieve perfect measurements.
"Families don't understand why we're tracking weight and food intake."
Explain the "why" upfront. Let families know that monitoring nutrition helps prevent avoidable health declines, hospital admissions, and slower recovery from illness. Transparency builds trust and often leads to families flagging concerns earlier.
What good nutrition monitoring looks like in practice
- MUST screening is completed at the start of care and repeated regularly based on risk level
- Weight and food intake are tracked consistently and recorded digitally
- Care plans specify what to do if appetite changes, weight drops, or MUST score increases
- Carers know why they're monitoring nutrition, not just what to record
- Alternative measurement methods are used when standard approaches aren't possible
- Managers review nutrition data proactively, not just when something goes wrong
- Reassessment happens automatically when people move between care settings
- Families and healthcare professionals are kept informed and involved throughout
This isn't about adding paperwork. It's about embedding a structured, evidence-based approach to something that already matters: keeping people well-nourished and healthy at home.
Key takeaways
- The MUST score is a simple, evidence-based tool that identifies malnutrition risk using BMI, weight loss, and acute disease effect
- Alternative measurement methods (ulna length, MUAC, subjective assessment) ensure everyone can be assessed even when standard measurements aren't possible
- Each risk level requires a different response: routine monitoring for low risk, closer observation for medium risk, and immediate intervention for high risk
- Reassessment when people move between care settings prevents nutritional risk from being overlooked during transitions
- 93% of people at risk of malnutrition live in the community, making domiciliary care a critical setting for early identification
- Technology can help embed MUST screening into daily workflows, making it easier to track, act, and evidence your approach
Malnutrition doesn't announce itself loudly. But with the right tools, systems, and protocols, care teams can spot the early signs—and intervene before health outcomes are compromised.
Want to learn more about how Birdie supports nutrition monitoring and clinical observations? Explore our care quality features or read our guide on how to write daily care notes.
Published date:
February 25, 2026
Author:
Lucy Ogilvie
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