The new Ramis is sleekly suited - "If I were casting me now it would have to be as a doctor or lawyer," he acknowledges - the professions he originally intended to try to join - and not the skinny mad scientist type he played in the Ghostbusters films (which he also co-wrote / produced / directed). "I was a heavy smoker," he explains, "and put on about 15 pounds for every substance I gave up."
Motivation for such a major life change may have included the premature deaths of some of the other comic geniuses he worked with - like John Belushi. But it might also have something to do with satisfaction of his second marriage to Erica Mann (they fell in love when she assisted him on a film called Paradise) and second-time fatherhood to boys aged six and two. "I do like spending time with my wife and children," he says. "I'm not that motivated really - I'm definitely not a workaholic. I like a nice empty schedule now. I'm something of a rarity in Hollywood."
It was not always that way for the moving force behind many of the greatest comic movies of the past 20 years. It is hard to imagine that the brain behind National Lampoon's Animal House would have preferred an evening in with the missus and kids to a night out with the lads. "Yeah, well, I went through that period," Ramis ruefully grins. "I got married the first time out of college [Washington University in St Louis] and kept fraternising - that was probably the death of my first marriage. It was very like the Animal House experience."
He's not happy with his new body image, he says, although he looks younger than 51 years and is, in many ways, more handsome than when he was young and gawkily thin. That's one of the reasons - aside from boundless talent as a director - that he prefers to stay on the other side of the camera. Other actors are delighted that he is there because he's such fun to work for, which helps explain why he has such a tightly knit "frat-pack" of regulars, such as Andie MacDowell, Bill Murray, Chevy Chase and, now, Michael Keaton, who wants to work with him again.
As a comedian and actor, Ramis knows that most of the funniest moments in life are spontaneous. So he gives his actors their heads to develop their own comedy "beats". ("We talk of comedy in beats because when improvisational comedy developed in the US it was parallel with jazz, and there was this hipster, beatnik parlance that developed.") They don't adlib, they improvise. "Adlib is saying whatever comes into your head - improvisation is a guided process working closely with the script," he explains.
Take the meatloaf scene in Multiplicity, which stars Michael Keaton as a man who clones himself and when Clone One isn't enough, tries again and gets a second. "The scene just says that Clone Two will show his wife [Andie MacDowell] how to wrap meatloaf. I told Michael `here's a chance to fly'." Before the scene was a "wrap", the entire cast was in hysterics. Isn't this unorthodox method of film-making crazy, wild, risky - and expensive? Ramis grins. "Film is cheap! Once the scene is set you might as well have fun with it."
He went straight into making big movies, he says, so he never had to rise to the challenge of the small budget. After abandoning the idea of medical or law school, and being "a draft dodger" during the Vietnam War, he became a film writer on a local paper in Chicago and got sent on "junkets" to film sets. "My first production story was on a film about the Molly Maguires, a radical terrorist labour group of US coalminers, with a blacklisted writer and director, and I was thoroughly radicalised. Then I did a big junket to South America where Louis Gilbert was directing Harold Robbins's The Adventurers - a totally trivial and excessive film - and then on to Hollywood to see Paint Your Wagon - a big-budget Paramount film, where they couldn't use the set because of rain 11 days in a row!"
He made his directional debut with Caddyshack, starring Bill Murray and Chevy Chase, which he co-wrote with the late Doug Kenney, whose name inspired the lead character Doug Kinney in Multiplicity. "I had always been fascinated by people who made me laugh. When I was little I used to like the great screen adventure heroes like Errol Flynn, but I moved on to want to be like Cary Grant, Jerry Lewis or Danny Kaye. Then I realised that people write these things, they direct these things - all that was missing was the belief that I could earn a living at it!"
His films continue to appeal to university frat-pack types, which is one of the reasons he turned the protagonist in Multiplicity into a blue- collar construction worker. "He was originally a man in a suit. I'm torn between wanting to make a film that everybody sees, and realising that I can't really converse with a certain section of the audience. When I worked at Second City in Chicago, where I got my training in comedy, we were told `work from the top of your intelligence' - and I see so many films, especially the two- and three-hundred-million dollar ones, that are not working from the top, but from some least-common denominator!"
Multiplicity works from a lower one, he concedes, than Groundhog Day - which attracted praise from "every spiritual discipline, from psychoanalytic journals - we knew that film had deep spiritual value!" Groundhog Day is a film that speaks to everyone who's ever felt that they're in a rut and don't have the power to change things. Multiplicity is for the stressed and overworked. Rewritten from a short story by Chris Miller, it is about the dream of "creating time". "My whole life's an emergency," Keaton wails. "It's like work is first, my family's a close second and I'm in third place bringing up the rear!" Multiplicity dispenses with any deep philosophical or ethical agonies about cloning and deals with the consequences. "The genetic engineering is just a magical device - I wasn't interested in the science or ethics," Ramis confirms.
What made him decide to do Multiplicity? "We were shooting Groundhog Day and probably no one feels busier than a film director when he's shooting - you have absolutely no personal time. So when I read the story I felt this really does describe modern life. But I decided the film couldn't just be about being too busy. It would have to explore why we're being pulled in so many directions. It's about the divided self. We're told when we're young that we should be so many things. Society was telling me to be a sports hero, movies to be an adventurer, a great lover and at the same time a stable husband and father."
Something had to give - as it does in Multiplicity. But, like Doug Kinney in the film, Ramis has found a new serenity. He's turning his back on the high-octane life of LA and moving back to Chicago, where he was born. "I wanted to see if my sons might have a more normal, stable and wholesome upbringing in Chicago than in LA. My daughter grew up fine, but is such a Californian kid!" he says expressively.
He also has another motive for his move away from "La-La Land" to the fresher air of "The Windy City". "No one has defined Chicago in films the way Woody Allen has Manhattan, or Barry Levinson did for Baltimore." And he rubs his hands in gleeful anticipation, while his myriad reflections in the over-ornate mirrors of the Dorchester multiply his enthusiasm over and over again.
n `Multiplicity' opens on Friday