Lady Gaga's fitness trainer was in for a surprise when the pop singer turned up in a quirky outfit for work out sessions in the gym.

The 'Poker Face' hitmaker approached celebrity fitness guru Harley Pasternak last year to tone up her body in preparation for her exhausting 'The Monster Ball' tour.

'She came to me because she wanted to find a lifestyle that was healthy and something she could handle while she was on the road. I'll never forget the time I looked out of office door and there she was. She was dressed in a pair of 12-inch heeled boots, shooting basketball hoops,' he said.

Pasternak also revealed that he has created a line of healthy snacks to mail to the star while she travels the world, reports torontosun.com

He added, 'She loves potato chips and peanut butter so I was inspired to create a line of potato chips and peanut butter bars that we ship to her wherever she goes.'