Basically the answer is no. Check out the study conclusions below or click the link to see the entire article.
"I guess anything is better than nothing, but we were a little bit underwhelmed with the exercise intensity of some of the exercises,� says Porcari. The Wii Fit is a very, very mild workout. Okay, first let�s put this into perspective. As Porcari suggests, choosing Wii Fit over typically sedentary video games is a good decision. According to this study one would burn double the calories by playing Wii Fit. But users need to keep in mind that Wii Fit itself is no panacea.
Since using the Wii Fit alone may not produce results that meet recommended physical activity, guidelines notes study author Alexa Carroll, M.S., it is important that individuals participate in additional exercises to effectively reach these guidelines. In other words, Wii Fit shouldn�t be your only workout."
Wii Fit or Wii Bit? ACE FitnessMatters July/Aug. 2008
My opinion of wii fit is much like the Condescending Willy Wonka Meme
In other words do real workouts if you want real results that last
