The 28-year old singer told Jay Leno on Friday that she underwent intense preparation for the shoot, by going on a cleansing mode and taking lots of vitamins and supplements, Us magazine reported.

Katy Perry
Katy Perry. Pic/Santa Banta

The ‘Wide Awake’ hit maker said that she changed from coffee to green tea.

Perry added that she was really in the zone and just wanted to be glowing for the cover, which was shot by famed photographer Annie Leibovitz on a farm in Upstate New York.