This is not to dogpile you, just as an aside since you were open to other POV: The WiiFit LIES. It told me I'm obese, which I am, and then it told my pre-teen (at the time) son he was as well, and he most certainly was not. The WiiFit is fun, but it definitely is not a good judge of body size.

(And BMI really is a crock, but I'm sure you've read that somewhere from the other links people provided.)