I'm not convinced by the accuracy of the readings...at least not the ones on the machine at my local gym.
I did one recently for the first time in about four months.
My one prior to this was when I was at my fittest - regular weight training, circuits, kayaking, biking and swimming plus pt sessions weekly.
The most recent one was after quite intensive cancer treatment - daily radiotherapy, weekly chemo, plus a deep vein thrombosis which left me unable to walk more than ten steps for a good week or so.
Obviously, my physical activity ground to a halt and I can see the muscle wastage - I had those saggy old man muscles whereas before I was nicely toned and had an athletic build with noticeable muscles especially in the legs. It's not just the.lack of exercise, chemo strips out a lot of the 'goodness' and muscle wastage is a side effect of that.
However, on the road to recovery now and starting to train again, so stepped onto the machine to give myself a baseline point....
Other than my weight going up a bit, my boditrax reading was pretty much the same as my pre-treatment one...when actually by sight I look like a before and after photo in the wrong order!
So I'd take any numbers with a big pinch of salt and just focus on what physical changes you can see and feel.