Mariah Carey is getting ready for her tour and she has lost an estimated 15 pounds in the process. “She’s on a healthy diet and has been working out a lot,” says an insider.

But making sure her body is in tiptop shape is nothing new for the 5-foot-9 Mariah, who went through the same slim-down process before her 2006 Adventures of Mimi tour.

So what is the difference now? This time her success may be permanent.

“Mariah’s thrilled with her body, and she’s determined to keep it,” says a second insider. “She’s really trying to make healthy eating a way of life – not just an emergency fix between tours.”

Recently, Mariah’s been stocking up on lean protein and veggies, but her new regimen has more to do with her mind. “She’s learning that a treat or two doesn’t mean she’s blown everything,” says the second insider. “She just stays longer at her next workout.”

Sessions with trainer Patricia Gray have become routine. “She swims and does lots of crunches,” says the first insider, noting the abs Mimi loves to flaunt. “She never wanted to get stick thin,” says the second insider. “Now she’s found a weight she thinks is perfect.” [source: Life & Style]