The percent underweight is one way of expressing how underweight a person is. This can be monitored over time to determine how well the person is responding to an intervention.


Patient selection: actual body weight < ideal body weight



(1) actual body weight in kilograms

(2) ideal body weight in kilograms


percent underweight =

= ((ideal body weight) - (actual body weight)) / (ideal body weight) * 100%


The inherent problem is determining the ideal body weight. This must take into account:

(1) age

(2) gender

(3) race

(4) body frame or build

(5) any amputations

(6) percent body fat (a small percent of body is desirable)


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