John, 65, said that he is worried about the 'frail' 26-year-old pop star, as she travels for her 'Born This Way' Ball tour, reported Contactmusic.
"I look at Gaga and I think, 'How does she do it?' I talk to her mum and dad about it. They worry.
"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. 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," John said.
Lady Gaga is also the godmother of John and his partner David Furnish's son Zachary.