Just FYI for Melbourne people, there's a place called BodyScan in Hawthorn, that has a special on currently for a whole body (DEXA) scan which shows body composition. It is free, with Medicare charge for the post-scan consultation. In the consultation, they give you a breakdown of fat and lean muscle mass, and tell you exactly what your target weight is. You also get an exact number of your resting metabolic rate, and how many calories you should eat for both maintenance and weight loss.
I have no affiliation with them, but was very impressed with my scan, thought it was really worthwhile. I prepaid a second one so I can compare it after surgery and see how much fat v muscle I've lost.
You can see a sample scan on their website.
http://www.bodyscan.com.au/