There are actually better exercise games out there for the Wii than WiiFit.I remember reading a review by an author who reviews video games and is also in shape. And in his review he said WiiFit said he had a BMI of 24.15 which makes him "overweight" according to the game. The problem is he's currently at 7% body fat, so he's not overweight. The game actually recommended him to loose 14lbs, but he only has 12.5 of fat on him. So WiiFit is encouraging him to loose muscle.
Here is a link to the Amazon Discussion Page for WiiFit where the above mentioned review list better alternatives for Wii Exercise games than WiiFit.
Just look for the post by Alexander Lucard.
And here is a link to Alex's blog and a post where he explains why WiiFit is bad.
10 Reasons Why WiiFit SucksHopefully this is helpful to some of you out there, and helps you get more out of your video game exercise time.