Is the wii fit accurate?

I went on it and it said my bmi wazs 17.73

So I was playing on the activities and did a 30 minute run and stuff, and now it's saying my bmi is 17.85 or something.

I mean wtf? Would I not have lost weight if I did exercise?

It may have to do with you standing slightly different.
Or, it could be because muscle weighs more than fat and therefore may have add a couple of ounces.
However, if you are taller than 5'6 then a BMI less than 20 is good.

maybe you didn't stand or whatever right the first time.so when you got weighed the 2nd time it had up the right weight or something...