The Impact of Weight Loss Scale (IWLS) is a subjective measure of a patient's perception of weight loss and change in body image following an illness that has caused a significant reduction in body weight. The authors are from the New York State Psychiatric Institute in New York City.


The instrument consists of 9 items related to the person's weight loss.



(1) All 9 items are phrased in the same direction of being concerned about weight loss.

(2) There is no neutral response for "neither agree nor disagree"



strongly disagree






strongly disagree




= SUM(points for all 9 items)



• minimum score: 9

• maximum score: 36

• The higher the score, the greater the concern about weight loss.

• In patients with HIV/AIDS, higher scores were associated with greater depression, reduced quality of life, and more marked nutritional deficits.

• The result can be converted to a 0-100% scale using the equation:

((IWLS) – 9) / 27 * 100%


Performance (page 455-456):

• The authors found the scale simple, reliable and quick to administer.

• It has good internal consistency, a unidimensional factor structure and concurrent validity.



• The scale could probably be reworded to measure the impact of weight gain.

• The scale would probably not work well for a patient with anorexia nervosa or bulemia, since the person tends to imagine that his or her body is too fat as it is. It might be interesting to see if the IWLS score would change during therapy, as a measure of changing awareness.


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