Peter Andre is desperate to gain weight.

The ‘Mysterious Girl’ singer is currently spending most of his free time in the gym because he needs to be in the “best shape” ever for a forthcoming mystery venture.

He said: “I’m working out like a demon at the moment because I’ve got a very exciting secret project coming up which means I need to be in the best shape of my life. I’m working my backside off every day!

“I’ve got a personal trainer and I’m aiming to put on 10lbs of lean muscle in a month.”

Although Peter - who has children Junior, four, and two-year-old Princess Tiaamii with ex-wife Katie Price - is finding the exercise part of his regime easy to follow, he is finding it tough sticking to a strict diet.

He explained: “It’s really tricky as I’m not meant to be eating carbs at the moment, and as you all know, I love my pasta. It’ll be worth it in the end though.”

However, the ‘Behind Closed Doors’ hitmaker is willing to lapse his food plan when bonding with his family.

He added: “I took the kids to a premiere of ‘Bob The Builder: The Legend Of The Golden Hammer’ at the weekend and they loved it. I took my mum along as well, although I’m not sure that it’s her type of film! She loves doing anything with the kids, though.

“Even though I’m watching what I eat at the moment, I had some popcorn. You can’t go to the cinema and not eat popcorn - it’s just not right!”