An inexpensive tape measure can provide a quick way to measure waist circumference.  BMI together with waist circumference is an effective way to assess chronic disease risk in a wide variety of patients.

“In the past, undernutrition and chronic diseases were seen as two totally separate problems, despite being present simultaneously. This dichotomy has obstructed effective action to curb the advancing epidemic of chronic diseases. For example, the prevailing approach of measuring child undernutrition on the basis of the underweight indicator (weight-for-age) can lead to gross underestimation of the presence of obesity in populations that have a high prevalence of stunting. Use of this indicator could lead aid programmes to feed apparently underweight people, with the undesirable outcome of further aggravating obesity.”  (WHO, 2003)