The secret of a perfect body? Good food and plenty of it, says New York's favourite nutritionist.
Five minutes in conversation with Oz Garcia is all you need to become convinced that here is a man clearly addicted to coffee. And not the instant, watery kind, but probably a shot of espresso on waking, followed by constant hits throughout the day.

How else to explain his being so alert, so kinetic? There is a level of energy to him that is palpable. Yet this 48-year-old New York nutritionist, currently the city's hottest diet guru, ministering to fitness-obsessed New Yorkers, jet-setting celebrities and pin-thin supermodels, hasn't had a cup of coffee for 20 years.

In Garcia's world, caffeine is poison, as dangerous to your body as weed killer. The energy burst he sustains 24 hours a day, seven days a week is, he says, simply from food.

Food? It's not the answer you were expecting, but then neither were clients Robert De Niro, Winona Ryder, Donna Karan, Nicole Miller and supermodels Veronica Webb, Daniela Pestova, and Yasmeen Ghuri. They too sat in Garcia's Manhattan office hoping that Garcia would dispense a magic pill, wave a wand and restore them to perfect health, only to be told food was the answer.

"People come to see me with problems ranging from overweight, mood swings, constant fatigue, jet lag, and everybody expects a magic bullet, a quick fix," he says, conceding that New York is the city of instant gratification.

Garcia, however, is the champion of the slow fix, which you can't imagine would make him very popular. The fact that he is (his book, The Balance, is an American best-seller), he says, proves that his theory of eating works.

Of course, Americans would not be queueing up to buy a book if it was just about better nutrition. The key to the book's - and Garcia's - huge popularity is that The Balance claims to help achieve permanent weight loss without dieting. "What I do with The Balance is X-ray your metabolism and then custom design an eating plan for you," Garcia says. "When you're eating the proper foods for your metabolic type, you don't have to count calories. Dieting fails because the body goes into starvation mode, and then you put on weight when you start eating again."

Garcia's programme, based on the scientific work of Dr Roger Williams and Dr Barry Sears, (author of The Zone) suggests that each of us has a metabolic body type (slow, medium, fast) which determines the rate at which we then burn calories.

Once you identify which type you are, you can eat foods that you burn easily and avoid those that linger in the system and turn to fat. Slow burners, he says, should stay away from wheat products, while fast burners might handle some grains, but should go slow on certain fruits.

While two thirds of his clients test as slow burners, Garcia warns that people who are naturally thin, if not eating metabolically, battle with fatigue, mood swings and depleted mineral stores.

To determine which type of burner you are, Garcia asks 50 questions, encompassing food cravings, energy levels, sleep patterns and libido, to identify what your fat cells do or don't do when a donut comes near. Garcia and his many clients swear that as well as weight loss, eating to match your metabolic type brings about increases in energy, relief from PMS, and a decrease in mood swings. It usually takes three to six months to bring your body up to speed.

There are few direct edicts in The Balance other than no caffeine or wheat, both of which he swears throw the body out of balance. (He adds that the French breakfast of coffee and a croissant is a disaster. "They would hate me in Paris.")

"I encourage moderation. The programme is flexible. You avoid the foods that do not work with your metabolism, but if you are at party and go off the programme for a night, you just get back on the next day."

Garcia is now in such demand (he was voted Best Nutritionist in New York by New York magazine twice), he finds himself turning clients away. He charges $4,000 for a series of 12 sessions, and will take you on only if you swear to commit to his programme.

"I am very selective. If you won't dedicate yourself, I won't work with you. I turn away two out of every four people I meet with."

Of course in New York, the idea that you may not make the cut only makes people more desperate to be among the chosen few. Currently, he is working with Olympic athletes to get them into peak condition, jet-lagged models and even chefs at some of New York's finest restaurants. "They graze all day in the kitchen. I have to show them how to keep their energy levels up by eating in balance."

But isn't having a personal nutritionist, getting metabolically typed, simply a rather trendy indulgence? Aren't we all equipped with instinctive knowledge on how to eat? Garcia says no, which is why, along with personal trainers and naturopaths, nutritionists are becoming mainstream. "We don't eat like our ancestors, who ate lean meat and coarse grains. Today we have so much poor quality, pre-packaged food at our disposal that is bad for our system, we have to learn to distinguish the good from the bad."

Garcia was not born with a burning desire to become a nutritionist. He fell into it by accident. Working as a freelance photographer 20 years ago, he was dispatched to a holistic health centre in New York to photograph a speaker. He put out his cigarette, walked into the lecture, and came out a changed man.

He returned for more lectures, then began reading maniacally into the relationship between nutrition and health. He quit smoking and caffeine, changed his diet and started running.

Fellow athletes, noticing his increased level of fitness, began asking for advice, and a consulting practice was born. He has no medical qualifications, although he has studied at natural health institutes in the US.

"I used to be an easy target for conventional doctors because I didn't have the usual letters after my name. But given my success, it has slowed down. I now get referrals from doctors."

After 20 years of metabolic eating, Garcia looks closer to 40 than 50, a perfect advert for his own programme. "My generation is now obsessed with retarding ageing and increasing energy. We are all going to live longer thanks to modern medicine, so we all want to know the role foods can play to maintain our careers, our libido."

Well sure, boomers turning 60 want to feel 40, but why do supermodels barely 25 need to feel young and in balance? Garcia says the models who find their way to him are doing the work now so they won't be washed up later.

"Smart models look at the profession like an athlete. They know they have to work out, maintain their energy and appearance, avoid coffee and cigarettes (models?) and keep their stress levels low. They are the ones who will have the longest careers."

Tall, skinny girls with names like Kate, Jodie and Naomi, please note.