Body Mass Index (BMI) This is the most commonly used index of over or underweight Body Mass Index = body weight ( Height) squared ClassificationBMI (kg/m2)Associated health risks UnderweightLess than 18.5Low Normal Average Overweight Moderate Obese class 1 Obese class 2 Obese class 3 Greater than – – – 39.9 Greater than 40.0 Increased Moderate inc. Severe inc. Very severe inc.

Body Mass Index

Classification by BMI may result in an individual being classified as overweight or obese, when in fact thay have a relatively low % body fat but a large muscle bulk. Eg. – body builders Weight = 130kg, height = 1.90m BMI = 130/(1.90)2 = 36 = obese class 2

Body Composition The body consists of 2 main compartments The Fat Mass (FM) - all the chemical fat in the body. The Fat-Free Mass (FFM) – muscle, bone and water There are many methods of assessing body composition ( see next lesson)