No wonder he's always hiking! 'Fat boy' Rob Kardashian enjoys a workout with a mystery brunette... as rapper The Game lets slip that they are dating

He's developed a strong passion for hiking after vowing to lose the 40lbs he put on in the wake of his split from Rita Ora last year.
But it would seem Rob Kardashian's sudden interest in the world of exercise could have something to do with a stunning new brunette.
The 25-year-old reality star seemed to be in great spirits as he embarked upon a workout in the Hollywood Hills with his enviably toned pal.

Mystery lady: Rob Kardashian was joined by a brunette pal as he embarked upon a gruelling hike in the Hollywood Hills on Wednesday

Beaming from ear-to-ear as he pounded the pavement alongside the gorgeous female on Wednesday, the sock entrepreneur couldn't have looked happier to be throwing himself into his exercise.

The pair's outing comes as Rob's pal, The Game, let slip that the Keeping Up With The Kardashians star is secretly dating the mystery lady.
The 33-year-old rapper told photographers that the couple have found romance, but are hoping to keep their relationship quiet for the time being.

Keeping the endorphins flowing: The pair seemed to be in high spirits as they pounded the pavements together

New romance? Rob's rapper pal, The Game, told photographers the pair are quietly dating

However, a representative for Rob Kardashian declined to comment when contacted by MailOnline about the claims.
Whether Rob and the mystery girl are dating or not remains to be seen, but they certainly looked happy and relaxed in each other's company on Wednesday.
And the brunette is evidently a great influence on the reality star's diet and exercise regime, as she was showing off her incredible washboard abs in a skimpy grey crop top as the pair got to work.

Joker! Rob appeared to be playfully poking his tongue out at his friend as they shared a joke together

Fitness guru: The brunette is evidently a great influence on the reality star's diet and exercise regime, as she was showing off her incredible washboard abs in a skimpy grey crop top as the pair got to work

Rob's pal teamed her barely-there top with red jogging trousers, pink trainers and had a pink jumper tied around her waist to ensure her enviably flat stomach was well and truly the centre of attention.
Wearing dark sunglasses to shelter her eyes from the strong Californian sun, the girl wore her hair scraped back off her face, and held an iPod in her hand as she pounded the pavements.
Rob opted for traditionally slimming black for his afternoon of exercise, teaming baggy shorts and a T-shirt with a beanie hat as he enjoyed a day out with his lady friend.

Enviable figure: Rob's pal teamed her barely-there top with red jogging trousers, pink trainers and had a pink jumper tied around her waist to ensure her enviably flat stomach was well and truly the centre of attention

Working hard: The sock entrepreneur has been sticking to a strict diet and exercise regime in recent weeks

And this is not the only time the pair have been spotted together, with Rob seen enjoying a tender hug with his new friend in Runyon Canyon last week.
The star is embracing a new healthy lifestyle, and is thought to be following the 60 Days of Fitness exercise and healthy eating programme advocated by The Game's younger brother BWS Byrd.
Taking on board his self proclaimed 'fat boy diet', the star has been constantly tweeting pictures of healthy meals, and has vowed to lose the 40lbs he claims he gained in the wake of the breakdown of his relationship with Hot Right Now singer Rita Ora.

Comfortable: Whether Rob and the mystery girl are dating or not remains to be seen, but they certainly looked happy and relaxed in each other's company

The pair parted ways on fairly acrimonious terms late last year, with Rob claiming the platinum-haired bombshell had cheated on him with 'more than 20 dudes' in an angry Twitter rant.
He later deleted his comments and then attempted to backtrack by belatedly pretending he had not been referring to his most recent ex-girlfriend.
Rob said of the romance in a recent episode of Kourtney And Kim Take Miami: 'All I did was waste a lot of money and gain 40 pounds. I need to focus on me. That’s all I wanna be about.

Keeping it in the family: Rob and sister Khloe cheered on Lamar Odom at the Los Angeles Clippers game on Wednesday night

Centre of the action: Rob has vowed to lose the 40lbs he gained in the wake of his split from ex-girlfriend Rita Ora

'Every time she messed up, I took her back for over a year now. I just had to do that to make her hate me.'
Rob's sister Khloe added: 'Rob got out of a really weird relationship. They were actually together for about a year but Rob was never allowed to admit that they were actually an item.
'Because she's in the entertainment industry, she wanted to present herself to the world as a single girl. I think Rob got really depressed through this relationship.'

Getting close: Rob and his mystery lady were spotted hugging at Runyon Canyon in Los Angeles last week

Health kick: The reality star has been constantly uploading pictures of healthy and nutritious meals to his Twitter account