Yes and no. UK series 1 has now finished. Aussie finished too but has been replaced with series 5 USA (families). Sky 1 have been showing USA series 3 (i think). So as of today 2 series are running.
However,
Biggest loser UK series 2 starts TOMORROW on Living (again get set your timer cos it's at 3am)
(I'll do a post actually telling people.)
HTH