Just as Kim Kardashian hinted at Bruce Jenner's personal "journey," the former Olympic athlete has yet again fuelled speculation that he is slowly transitioning into a woman.

The 65-year-old was seen sporting a plumper pout on Tuesday (27 January) after reportedly having injections in his lips to make them looking fuller.

The reality star's hair is also longer and sleeker and often tied back in a ponytail.

It's the latest in a series of physical changes the former sports star appears to have undergone, contributing to his increasingly feminine appearance.

He has been sighted sporting hot pink nails, body slimming Spanx, voluminous blow drys, and suspiciously hairless legs, adding to the rumours that he is on course for gender reassignment treatment.

The transgender claims began in 2013 shortly after Bruce separated from his wife the Kardashian matriarch Kris Jenner. They officially ended their 23-year marriage by divorcing last September.

While Jenner has refused to comment on the speculation, in an interview with Entertainment Tonight, Kim said that it's "his journey to talk about," adding that he is "happier than ever."

"I think everyone goes through things in life, and I think that story and what Bruce is going through, I think he'll share whenever the time is right. I feel like that's his journey to talk about," she explained.

"He's our dad so we support him no matter what, and I think when the time is right he'll talk about whatever he wants to talk about. I just think it's his story to talk about, not really mine."

Last week, in a display of family unity and support, the Kardashian-Jenner daughters surrounded their father for a photo captioned: 'Family First.'

Bruce's "journey" will be the subject of an E! documentary to be screen later this year.