For a speculated/cool $400 million, Aussie fitness star and young rich lister Kayla Itsines has sold her hit health and fitness app SWEAT to US outfit iFIT – a global leader in fitness software and streaming content. Since launching the app in 2015, SWEAT now has more than 30 million users across 155 countries. Last year, it posted a profit of $99.5 million. In an Instagram post yesterday, 30yo Itsines reassured members that it was BAU at SWEAT. “I will still be your trainer, and all of our programs are not changing or going anywhere,” she said. With the backing of iFIT, Itsines said she will be able to offer more features and help it expand into other countries. That’s a lot of corporate huffy puffy…