I used it as part of a plan I had this past spring to lose some weight, along with other exercise and a change in diet. Kept up with it for about a month and lost a good 10-12 pounds over that time, so I know it certainly didn't hurt, but I can't say how much it helped because all the changes happened at the same time, for the same period of time. I did try it again here at my new place, using only the WiiFit and my new bicycle commute (I walked to my old schools) as my exercise and lost a little over that time, so I'm quite sure it can help, but given the stuff it offers, you probably shouldn't rely solely on the WiiFit for your exercise regiment.
