I know you'll all be used to hearing this phrase but...

My scales lie!

Honestly... If i stand in the middle they say i'm about 6 pounds heavier than if i stand where my feet naturally go (i've got size 12 - US 13 - feet so standing in the middle means i'm on tiptoes and the needle jumps around quite a bit).

I guess i'll just have to make sure my feet are in exactly the same place every time.

Sucks though coz i just bought the scales and they weren't cheap (but they were the only ones i could find that went above 19 stone, unfortunately).