I can see Wii Fit sales going one of two ways.

1) It's a fun video game that draws a reasonably large audience and sells somewhere in the 10 million range.

2) It actually works as a weight loss device.  Then word of mouth takes over and someone like Oprah or Ellen have it on their show.  If this happens, it could sell 50 million, maybe even 100 million.

Do we have any reports from Japan whether people are losing weight using it?

http://www.4colorrebellion.com/archives/2008/04/02/the-great-experiment-wii-fit-%e2%80%93-final-report-or-how-i-lost-10-pounds-in-7-weeks-by-playing-video-games/

So now I guess we wait to see if Oprah does a show on it.

If this does actually work for others like it did for this guy, then forget about GTA IV being the best selling game this generation.  Wii Fit will clobber it.

Nice find tabsina. If you look at the comments you see alot of people beening convince to buy wiifit after the article. Sales by word of mouth for this game for things like this will make this sell amazingly.

I guess there will be tests like this everywhere soon. I read that DN, the biggest swedish newspaper, is doing a long "does it work" test instead of a normal review.

Wii Fit and GTA both have one thing in common which will (certainly) help Wii Fit sell; and that is free press. For Wii fit this is the progression of press that I see happening:

1. Wii Fit is released and most local and national news broadcasts have a blurb about Nintendo's unusual weightloss videogame.
2. Weeks later Wii Fit is covered on shows like 20/20 and 60 Minutes and actually gets a (generally) positive response from people in the fitness industry, and it is demonstrated that you can lose some weight with Wii Fit.
3. Weeks later Wii Fit returns to local and national news broadcasts as it is being used in physio therapy and in retirement homes as a way to provide excercise for people with limited capabilities.
4. Weeks later Wii Fit hits Oprah and she gives away a Wii (with Wii Fit) to every member of her audience
5. The next day local and National news brodcasts announce that Wii Fit was on Oprah and was given away to every member of her audience

 I added the last step.