No Doubt take their personal trainers on tour.
The Don't Speak rockers - who have recently reunited following a four-year hiatus - admit they are no longer able to cope with the rigours of being on the road unless they are fully fit.
Bassist Tony Kanal said: "We travel with two personal trainers. We're getting older and we can't party like we used to."
The group have to rely on professional fitness experts because they attract too much attention if they go to a gym.
Singer Gwen Stefani said: "I have to wear make-up to the gym because I get some dude doing sit-ups next to me and surreptitiously taking pictures.
Gwen - who has two sons Kingston, three, and 10-month-old Zuma, with husband Gavin Rossdale - also revealed the group are touring without any new material because she was too busy eating to write any songs.
She added to the Chicago Sun-Times newspaper: "Honestly, it's procrastination. My plan was to get pregnant and write a record, but instead of writing, I just ate all the time.
"Writing is always really hard for me - I hate it and hate it, and then I do it and I'm happy it's done. I was blocked and I needed to get inspired, and I thought playing live would get the creative juices flowing again."