Gary Barlow underwent a mystery operation on Thursday (12.01.17).

The Take That singer - who has battled with his fluctuating weight for years - told his fans he was spending his 17th wedding anniversary in hospital for a ''minor procedure''.

Taking to Twitter on Wednesday (11.01.17), he said: ''In for a little op tomorrow. Nothing serious. I'm really looking forward to sleeping all afternoon ! Lol (sic)''

Although the 45-year-old singer spent the rest of the afternoon sleeping off his anaesthetic instead of celebrating the marital milestone with his wife Dawn Andrews, the hunk appeared to be right as rein the morning afterwards (13.01.17) as he was up at the crack of dawn in order to work up a sweat on the running machine at the gym.

Alongside a blurry black and white selfie of him on the exercise machine, he wrote: ''30mins training done, 30 to go #bb (sic)''

Gary refused to divulge what the operation was for but set tongues wagging this morning when he joked that his ''face lift was complete'' and his ''breast implants were successful.''

The handsome star has been taking his health very seriously over the past few months as he was determined to lose weight and get in shape for last week's 'Let It Shine' debut.

He said: ''I wanted to look semi-decent. I didn't want the old moobs flopping away there.''

Although Gary spent his 17th wedding anniversary on the operating table and then snoozing off the surgery drug on the sofa, the heartthrob will no doubt mark the special occasion with his beautiful wife - who he met in 1995 - over the weekend.

The couple got married in 2000 and have three children; Daniel, 16, Emily, 14, and Daisy, seven, together.