Lady Gaga's diet tweet sparks controversy among fans, media(REUTERS)

According to FitSugar, she also works out five times a week for at least 25 minutes each day (however back-to-back spin classes would likely run at around two hours). To achieve her washboard abs, she is devoted to crunches, starting with basic crunches, modified reverse crunches, and double crunches.

For her firm buttocks, check out a video of Pasternak demonstrating Gaga's tush-toning routine, click here.

The pop star is also a veteran yogini; she reportedly visits Bikram and hot yoga studios while on tour, and has worked for years with New York-based teacher Tricia Donegan.