<prompt> Severe malnutrition is defined in adults with BMI less than18.5161311  <response>: Body mass index BMI BMI wt kg ht m2 Example: an adult of 70 kg with a height of 1.75 m has a BMI of 701.752 22.9 kgm2 BMI is a useful way of identifying under- or over-nutrition but cannot discriminate between lean body or muscle mass and fat mass 