gym no makeup

No more gas station snacks for Britney Spears!

The sexy pop singer has been working overtime on her fitness in preparation for her upcoming Femme Fatale world tour, which kicks off June 16 in Sacramento, Calif.

This comeback tour is huge for Spears, and she has a very busy six months ahead of her.

Once she wraps up her U.S. tour this August, Brit will perform all over Europe until mid-November, and she'll finish in Portugal. Whew!

Get a sneak peek at Britney's Femme Fatale set list, after the jump ...