Marc Jacobs is showing off his legs. Well, sort of — because nowadays he doesn’t really wear trousers, he prefers kilts. All the better to reveal his buff new body, perhaps?

This is, after all, the man who recently posted a Twitter update saying: “Running in NY tonight was amazing — the air is unreal. Life is good.” So just how has he transformed himself into walking whipcord and steel after years of highly publicised weight and drug issues? “I just try to eat well. I usually go to the gym for two hours every morning. I try to be in bed early and lead a pretty healthy life — for the most part.”

Mostly, of course, he’s just plain happy, both “with where I am in the world and in terms of relationships”. He is engaged to the ad executive Lorenzo Martone, although they had to postpone their hoped-for June wedding. “I’ve met someone I’m very much in love with, and he’s very much in love with me,” he says. “The idea of marriage is, I think, a commitment in its purest form.” He has moved back to America from Paris: “I haven’t lived in New York in a long time, so now I’m a resident here again, we decided to buy a house together. We both want children.” Even at work, it’s all hunky-dory. “I’m a bit of a cheerleader,” he says. “I have to stimulate people, or I feel it’s my role to stimulate people. So the better my attitude is and the better I’m feeling, the better everybody feels about being around me. What I give is definitely what I get back.”

What he’s trying to give me, however, is not the lowdown on his private life, but the inside track on his new fragrance, Lola, the follow-up to his last blockbuster, Daisy. Where Daisy (inspired by his love of Daisy in The Great Gatsby) was “white and sweet and innocent”, Lola is “warm, sexy — with reds and hot colours”. So why the switch in fragrance tactics? “By giving myself a contrast, I was able to do something that really held excitement for me. If I had done something lovely and pretty, it would just be another version of the same thing.” He does the same with each fashion collection, contradicting what has gone before it.

Refreshingly, with Jacobs’s perfume, it’s not all about top notes and fragrance pyramids, it’s about “having this very free, almost fashion, approach to fragrance — coming up with the mood, the spirit, then trying to put that into colours, to try to visually transmit some idea of what this fragrance would be, then work on the fragrance itself”. The name came first — he was adamant it had to be Lola. “It has always evoked that kind of seductive thing,” he says, referencing Lola in the songs Copacabana and in Whatever Lola Wants (Lola Gets).

And the smell? A little bit fruity, a lot floral, with a dash of vanilla and musk. Whether it is a hit is not his concern. “It’s not up to me if something is successful,” Jacobs says. “I can love something and say, ‘Okay, it’s time for me to let this go’, but then it’s up to the women out there. It’s the same with a dress. These are proposals, things that I believe in within a given moment. But then it’s up to you.”

Lola by Marc Jacobs, £45 for 50ml, is exclusive to Harvey Nichols. Released nationwide Aug 26; www.marcjacobsvipclub.co.uk

MARC ON...

His body “I’m a very black-and-white person. I’m feast or famine. I’ll work out seven days a week or none at all.”

Art “I got over intimidation from the art world when I realised that I was allowed to feel whatever I want.”

Tattoos “I have a really good attitude about tattooing. I was, like, ‘I’m not going to overlook what it means, or what it’s going to be like when I’m 80. I want to get tattooed today.’”

His muse “She feels right for this. Karlie [Kloss, his new fragrance muse] has a hint of naughtiness in her eyes.”

Fashion “I like the ‘nothingness’ of jeans and a T-shirt. I feel that’s about as close as I can get to the future, because it seems like something so old, it will always be there.”

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