The TV and radio star showcased his new look by going topless on the cover of this month’s Men’s Health magazine.
The 44-year-old posted an image of the cover to Instagram, before revealing his toned new look was all down to a plant-based diet.
"Over ten weeks I lost 9kg of fat and gained 2.5kg by eating nothing but plants and training every day until I was a flat pancake on the gym floor,” he said.
“This is me, with my shirt off on the cover of Men's Health, and I’m the first plant-based person to do so in Australia.”
Osher’s trainer, Chief Brabon revealed to the magazine: 'When we started, Osher’s body fat was 22 per cent. Most people didn’t realise he was carrying that weight because he had such a slim face. He had a broad, boxy physique.'
Osher also revealed that his fitness journey was motivated by mental health management after he decided to ditch his prescribed medication last year.
'I started this #MHtransformation as a way to help me manage life off of meds,' he wrote on Instagram.
'I hadn't been on antipsychotics for about 18 months before I started this.'
He continued: 'I'd shifted to a different medication for the OCD, however as I got better and better, the side effects now became more prominent than the symptoms - so me and my Dr decided to try life without them.
'Coming off meds in Dec meant that I needed to put management strategies in the place where they once were, I needed things to help me regulate my emotions and emotional responses - and resistance training was a large part of that.'