“Plus I had a bicycle rather than a car. Cycling is not a good thing to do, I’m all broken as a result of it but I did lose a lot of weight.”
Jeremy, who went on his travels with girlfriend Lisa Hogan, continued: “Where I was staying was separated from the small town by a mountain but it was much bigger than Everest.
“It was only three kilometres and I cycled it every day, I said, ‘I can’t have a drink unless I cycle into town.’ I wanted to get fit.”
During his extended holiday, the father-of-three admitted that he thought about getting a tattoo.
“I was this close,” he said, before recalling: “I actually went past the tattoo store and thought, ‘Come on.’
“A red star on my a**e is what I had in mind. But then I went wrong, I had an illness, I had an abscess…”
Jeremy was in Saigon when he was rushed to hospital, after seeking medical advice for the condition.
He commented: “I said, ‘It’s nothing, I just need a doctor to pop around and lance this little abscess I’ve got.’ She [the doctor] said, ‘Where is it?’ I said, ‘My abdomen.’ She said, ‘Does it hurt?’ I said, ‘Yes it does.’
“She said, ‘Which side?’ I said, ‘Left side,’ she said, ‘We’re sending an ambulance’… By the time I’d finished explaining, the ambulance was there…”
Jeremy said within three minutes of arriving he was on the operating table, as he praised the “fabulous” Vietnamese health care system.
However, he has still not completely healed: “[The wound] is now as we speak [oozing out] because you can’t close the wound.
“I’m leaking! I’ve got a skin disease as well.”
Jeremy was joined on the instalment by Spice Girl Emma Bunton, actor and star of ITV2’s Timewasters Samson Kayo and comedian Sara Pascoe.
The former hitmaker was asked about who the peacemakers are in the now-four piece, to which she remarked: “I think we all know each other’s characters so well that we deal with each other in different ways.
“We have different friendships, so we work really well together, that’s what is so good about us.”
The Jonathan Ross Show continues Saturday at 9.20pm on ITV.