An American have a cross-question in the region of counterbalance?

I am watching your version of The Biggest Loser and everyone is mortal weighed surrounded by stones and lbs. Like one lady weigh 23 stone and 6 lbs. Is this part of the metric system? I thought lbs be just used within the USA. How much is a stone? On the Austrailian version they be weighed surrounded by kilos..Im confused. A stone is 14 pounds,
And in Australia they I don`t know use kilos?
xo
We use stones cause it is simpler (ie a smaller number and bigger units). There are 14 pounds to a stone- so right to be heard, 9 and a half stone would be 133 pounds.