The 'Unconditionally' star gave a concert at Caesar's Palace in Las Vegas to see in the New Year and her rider demands included lots of vegetables and fruits.
According to TMZ.com Katy asks for: "Fresh vegetables AT ALL TIMES - including spinach/broccoli/celery/beets/carrots/kale, etc.
"Two large baskets of fruit - one must be tropical.
"Dinner must include a vegetarian option ... plus Quinoa or couscous. ALL meals must be low-fat and health conscious and cannot contain MSG."
Katy has separate requirements for her own dressing room, including fresh organic fruit - which must be sliced - crudités such as cucumber, broccoli, cauliflower and carrots with ranch dip as well as granola, dried figs and whole grain tortilla chips with hummus and guacamole to dip them in.
Katy allows herself one small indulgence to celebrate finishing a show, in the form of wine, listing "two bottles of Pinot Grigio and one Argentine Malbec" among her requirements.
The 29-year-old star is also a fan of keeping fit, and last year started channelling her energies into going spinning - a regime of tough indoor cycling classes - at the gym instead of going out clubbing.
A source said: "Katy believes the workouts have really been soothing her brain.
"A few years ago she would have released the energy by hitting the clubs and dancing the night away. But she's getting older now and wants to do things healthily."