Here's a success story.
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/

wii fit only works when you keep a healthy diet in the first place. the man said that he didnt decrease his consumption but removing fats salts sugers from the diet would make you lose weight naturally anyway and you can still eat the same amount of food regardless of exercise.

skipping meals puts your body in fat storing mode so you gain weight by not eating so its badder for you

reducing food portions is a good way too as obeese people tend to over eat in the first place

i know of a lot of fat people success stories with tv meals because of the reduced portions even tho it contains more salt and fat than regular meals and thats because of the reduction in over eating. a result they feel less hungry over time and dont crave as much food

exercise is a no brainer but theres no proof that wii fit makes you lose weight over regular exercise and keeping a healthyer diet.

most people dont change the diets because wii fit is a game