As a self-confessed sex-addict, 35-year-old Brand bedded up to five women a day when his comedy career took off in the UK, but said that once he fell for Katy, he had to own up about his old hedonistic lifestyle.
'I don't think she knew the extremes of it because I wasn't famous in America,' he said.
'I told her like an idiot, as I was so dazzled by the change.
'So I had to tell her, 'Look at what I'm not doing.' Yeah, she was shocked but she's a pretty solid person.'
He added that although he has less sex now that he is a married man, he has been able to hone his green-fingered skills.
'I can't believe I used to have sex 20 times a week, especially now I'm married,' he said. 'But now I'm a bloody good gardener.'
Asked if he would be able to just stick to one woman for the rest of his life, the former alcoholic and heroin addict said, 'I take it one step at a time - like with drugs, like with alcohol.
'Don't look at things as in 'rest of life'. Of course marriage is for life and that's what I wanted but anything for the rest of life can be daunting.'