The Made In Chelsea star was removed from the jungle just three days after arriving, and explained in a lengthy statement to fans that producers decided he could not longer participate once they discovered he'd been using steroids.
Speaking to The Mirror, his co-star Jamie said: "Spenny is great. He is my best friend and he has my full support. People make mistakes and he's made a big one.
"But to come out and be so honest about everything the way he has is so bold. It is very easy to hide away from things like this but he came clean. Sadly, that decision got him kicked out of the jungle. It's very unfortunate because he was doing so well. But as I said, people do make mistakes. He made a decision and he's not happy with it."
Spencer was a late arrival to the jungle alongside Ferne McCann and Vicky Pattison, but producers were forced to remove him from the show after he disclosed his steroid use.
In a statement to fans, he said: "The simple answer is that I screwed up, and have some explaining to do. Shortly after I arrived in Australia I told the production team that I was taking a steroid-based medication that had begun some weeks ago.
"When I started taking this programme of pills it was in preparation for a charity boxing match which, ironically, never took place. Vanity, I suppose, had been the reason for wanting to bulk up a bit for the fight. I had intended to come off the pills gradually, but there was no time to do this before I reached the jungle.
"My admission to the production team that I was still taking these pills led to the conclusion that it would be unsafe for me to stay in the jungle - a decision which I found extremely hard to stomach. I pushed back but ultimately the show's duty of care prevailed and bags had to be packed."
I'm A Celebrity bosses will not replace him.
Meanwhile, former Celebrity Big Brother star Austin Armacost spoke out this week to say ITV was right to remove Spencer from the jungle.
He told Daily Star: "As a certified personal trainer I don't understand why people put their health in danger simply for the sake of vanity. I am an all natural bodybuilder and I've never taken steroids in my life and encourage everybody to do the same. As public figures we should all help promote health and wellbeing not vanity & narcissism."
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