The singer, who is about to embark on a world tour, told the publication that she has been on a strict diet in preparation for the sexy shoot and the 90 shows she has lined up.
She said, 'I'm on a meal plan which absolutely sucks. But on Sundays I get to have a cheat day where I go buck wild and eat In-N-Out Burger.
'I'll work out, go to a vocal lesson, run through the entire set at rehearsals, go to dance rehearsal until 10pm and then go home and sort through e-mails concerning the production. I feel like I'm training for the Olympics!'
The 26-year-old, who married British comedian Russell Brand last year, said that she is looking forward to having a fragranced tour.
She explained, 'It's the first concert that's going to smell good. It's going to smell like you're in cotton candy heaven. It's a fun little nuance.'