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The 5 MUST steps (see algorithm)

Step 1

  • Measure height and weight to get a body mass index (BMI) score

Step 2

  • Note percentage unplanned weight loss and score

Step 3

  • Establish acute disease effect and score (unlikely to apply in primary care)

Step 4

  • Add scores from steps 1, 2 and 3 together to obtain overall risk of malnutrition

Step 5

  • Use management guidelines and/or local policy to develop care plan

Alternative measurements and considerations

Step 1: BMI

  • If height cannot be measured:
    • use recently documented or self-reported height (if reliable and realistic)
    • if the individual does not know or is unable to report his or her height, use one of the alternative measurements to estimate height (ulna, knee height or demispan)

Step 2: Recent unplanned weight loss

  • If recent weight loss cannot be calculated, use self-reported weight loss (if reliable and realistic)

Subjective criteria

  • If height, weight or BMI cannot be obtained, the following criteria which relate to them can assist your professional judgement of the individual’s nutritional risk. Mid upper arm circumference may be used to estimate BMI category in order to support your overall impression of nutritional risk
  • BMI:
    • clinical impression – thin, acceptable weight, overweight. Obvious wasting (very thin) and obesity (very overweight) can also be noted
  • Unplanned weight loss:
      • clothes and/or jewellery have become loose fitting (weight loss)
      • history of decreased food intake, reduced appetite or swallowing problems over 3–6 months and underlying disease or psycho-social/physical disabilities likely to cause weight loss

Other criteria

  • Further details on taking alternative measurements, special circumstances (e.g. those with fluid disturbances, plaster casts, amputations, critical illness and pregnant or lactating women) and subjective criteria can be found in the ‘MUST’ explanatory booklet (see contact details below to obtain a copy)


Full guideline:


BAPEN Office, Seven Elms, Dark Lane, Astwood Bank, Redditch, Worcestershire, B96 6HB

01527 457850 email –  bapen@bapen.org.uk

‘Malnutrition Universal Screening Tool’ (‘MUST’) for adults. November 2003, updated 2011
First included: June 2000.


Lead image: ronstik/stock.adobe.com