Elton John is concerned about his friend Lady Gaga's health, telling The Guardian that Mother Monster's hectic touring and work schedule leave her "frail" and undernourished.

Perhaps more disconcerting is that John said Gaga's parents, to whom she is famously quite close, worry about her welfare as well. "I look at Gaga, and I think, 'How does she do it?' I talk to her mum and dad about it. They worry," he said.

"She is frail, and she doesn't eat when she should do, and she's a girl, and it's tougher for a girl. She works really hard," John continued. "She will be in Denmark one night and Saudi Arabia the next. I know how tiny she is, and I do worry about her, yes."

Gaga and John are so close that the music legend chose the "Born This Way" singer to be the godmother of his one-year-old son, Zachary. The pair have collaborated artistically multiple times, including a medley performance of their hits at the 2010 Grammys and on the duet "Hello Hello" for the animated 2011 film "Gnomeo & Juliet." Gaga has said that the two will duet again for her next album, which she is reportedly working on concurrently with her "Born This Way Ball" Tour.

"My next duet, I believe, will be with Elton," Gaga told British talk-show host Alan Carr late last year. "I'm already working on my next album, and I played him a song that I wrote, and he really loved it. I don't want to give anything [else] away!"

John's concerns for Gaga's health are not without precedent. In January 2010, the pop star was forced to cancel a concert in West Lafayette, Indiana, when she experienced shortness of breath and a rapid heartbeat backstage immediately before the performance was set to begin. After that frightening incident, Gaga canceled dates in Atlantic City, New Jersey, and Wallingford, Connecticut, based on doctor's recommendations that she take time to recover from exhaustion.

Just two months later, Gaga appeared on the verge of collapse by the conclusion of a "Monster Ball" show in Auckland, New Zealand. Video from the performance shows Gaga sitting and even lying down during the final song of the evening, "Bad Romance."