13 Weeks: Tool Time
Measurements are fairly straightforward. I bought a MyoTape measuring tape, which is supposed to make it easier to take the measurements for yourself. It's a white plastic object with a spring-loaded measuring tape. You wrap the tape around yourself, hook the end of the tape back into the plastic body, and then pull it tight. In theory, then you unhook the tape and read it.
In my arrogant opinion, this device basically sucks. The problem is that when you release the tape, the spring loading pulls in the tape until it catches a ratchet of some sort. This can be anything from a half inch to an inch. You're better off with an old-fashioned sewing tape. Amazon has a bunch of them -- in fact if you have eleven friends, you can buy twelve of them for about 50 cents each.
Skinfold calipers are supposed to be a good method. You pinch up a fold of skin and measure its thickness, then use a chart (or compute a somewhat complicated formula) to get your percent body fat. I got one from Amazon for about $15.
But here's the problem: it's almost impossible to do yourself. One of the measurements you should take is on your back around your shoulder blade, and I defy anyone but a stage magician or a contortionist from a Chinese circus to do that for themselves, and I have completely failed to teach my cats to do it for me.
So that leaves the bio-impedance method. There are lots of devices for this; I bought a Withings scale. It basically runs the current from one foot to the other while weighing you, then connects to your wireless network and sends the data home, where you can look at it on the web.