TRADE UNIONS WORKING TO PROTECT THE 
HEALTH OF CONSTRUCTION WORKERS 
TRADE UNIONS WORKING TO PROTECT THE 
HEALTH OF CONSTRUCTION WORKERS 

BMI - WHAT IS IT? 

The Body Mass Index (BMI) is a measure of the weight of a person in relation to their height. It is used as a guide to indicate how overweight or underweight a person maybe, however we do not use it as the sole indicator to diagnose a weight problem. 
 

 WHAT TO EXPECT? 

The test is simple and just involves taking a height and weight measurement and sometimes the nurse will also take a waist measurement. 
 
Depending on the results of the test, we may recommend you see a GP for a further assessment. 
 
CLASSIFICATION   
BMI (kg/m2) 
 
   
PRINCIPAL CUT-OFF POINTS 
ADDITIONAL CUT-OFF POINTS 
Underweight 
<18.50 
<18.50 
Severe thinness 
<16.00 
<16.00 
Moderate thinness 
16.00 – 16.99 
16.00 – 16.99 
Mild thinness 
17.00 – 18.49 
17.00 – 18.49 
Normal range 
18.50 – 24.99 
18.50 – 22.99 
 
 
23.00 – 24.99 
Overweight 
≥25.00 
≥25.00 
Pre-obese 
25.00 – 29.99 
25.00 – 27.49 
 
 
27.50 – 29.99 
Obese 
≥30.00 
≥30.00 
Obese class I 
30.00 – 34.99 
30.00 – 32.49 
 
 
32.50 – 34.99 
Obese class II 
35.00 – 39.99 
35.00 – 37.49 
 
 
37.50 – 39.99 
Obese class III 
≥40.00 
≥40.00 
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