Its says in the manual do not use it on thick carpet. I use it on my carpet which isnt mega think but isnt thin either and it works fine.
The only problem you would have on a carpet is if its that thick its pushing on the under side of the board which would stop the 4 corner legs (which are the sensors) from touching the ground. --- GT: dantez72
My living room is carpeted, my kitchen is laminated. I tried it weighing me on the living room carpet and on the kitchen floor, it put me down as 1.5kgs heavier (sorry don't know lbs) than on the carpet, presumably because it absorbed the weight.
Ideally a thin carpet or laminate floor would be best, but if you can't do that, every measurement will still be on the same carpet, so your weight loss goal should still stand. If you lose 1lb, you will weigh 1lb less on the carpet and on the laminate.
I lost around 21lbs by doing it on carpet. Put the pad on a slab of MDF and it started working properly. The balance was fine before and after, though. I should imagine that the game where you step in time to the music is probably more pleasant on a carpet. --- "Sweet Christmas! Big-mouthed floating thingies!" Marine - the Doom comic