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 Normal18.5 - 24.9Average Overweight Moderate Obese class 1 Obese class 2 Obese class 3 Greater than 25.0 25.0 – 29.9 30.0 – 34.9 35.0 – 39.9 Greater than 40.0 Increased Moderate inc. Severe inc. Very severe inc.
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)