Celebrities such as Victoria Beckham have quietly followed Japanese style diets in order to keep their svelte figures. Now authors Naomi Moriyama and William Doyle reveal how it's done

Extract taken from Japanese Women Don't Get Old Or Fat (Vermillion)

My first day in the United States was a series of shocks. I landed at O'Hare Airport at 6 a.m. The drive from Chicago astonished me. I had never seen such huge highways, not to mention the flat land and a sky that seemed to go on forever. No matter which direction I faced, the sky took up almost my entire field of vision.

By 7 a.m., I had arrived at school. I was escorted to the student dining room and asked what I wanted for breakfast. 'Orange juice,' I said. I was offered a very large glass of orange juice. My eyes widened in amazement. I wondered, how could anyone possibly drink so much orange juice? Before I could recover from the shock of the super jumbo orange juice, I saw a student cut up several thick layers of pancakes and pour syrup over them until they were completely drenched, soaked and luxuriating in puddles of the sweet, sticky liquid.

Nobody ate like this in Japan and I assumed I never would either. Little did I know this was the beginning of my journey through the American way of serving and eating or, more precisely, the beginning of My Fat Years.

Though I loved practically everything about America, the food was at first an unpleasant jolt to my system. Japanese food and Japanese portions were what I grew up on, but Lewis University was in rural Illinois and there were no Japanese restaurants or Japanese ingredients nearby.

And soon I started to eat like my American friends too. The result: within a few months of arriving in America, I had gained more than 10 kilograms (and I stood five feet tall). Now I was pushing 57 kilos and bursting out of most of the clothes I had brought from Tokyo, especially my tight jeans.

I tried to work off the extra calories by running on a stretch of field behind the dorm. But it was in vain: I couldn't lose a gram. Soon it was winter and the Chicago area seemed buried in snow for half the year. I stayed indoors most of the winter. I got very little exercise.

Despite gaining more than 10 kilograms and missing veggies, I was thrilled to be going to school, making friends and acquiring American habits. Weeks and months went by fast. I spent two years in the Midwest without ever going back to Japan. Finally, after many happy days in the midst of the cornfields of Illinois, I returned home.

My family came to meet me at the airport and I immediately began gushing about how much I loved America. One of my aunts interrupted with a blunt question: 'How could you be so happy there? Look at you - you've got fat!' She was right.

Living in Tokyo again, I went through reverse cultural shock. Between the walking-intensive Tokyo lifestyle and my mother's home cooking, the extra 10 kilograms began to miraculously melt away. I didn't do anything conscious to lose the weight; I simply went back to my mother's Tokyo kitchen and the Japanese urban way of life. And suddenly one day I found I could easily fit into all my old clothes.

After a stint at Tokyo Disneyland, I went to work at Grey Advertising in Tokyo, where I thought I might enjoy a profession that combines commerce and creativity. I did enjoy it, but I missed life in the United States.

My first apartment in Manhattan had a tiny kitchen with a big refrigerator, a big oven, a sink and cupboards. There was no space to chop or prepare foods and no ventilation for cooking fish. I asked a colleague at the office, 'What's up with these Manhattan kitchens? They don't give you any space to prepare food. And what am I supposed to do with this refrigerator?'

She said, 'Well, most of us in New York go out to eat, bring a doggy bag home, put it in the refrigerator and heat it up in the oven the next day.' Wow, that makes sense, I thought. I like the efficiency!

When I went back to Tokyo to visit my family, my mother, in her typical fashion, asked, 'Are you eating well?'

'Of course, Mum, I live in New York! Lots of fabulous restaurants and take-away places. Plus, I have a microwave oven!'

'What do you mean you have a microwave oven?' My mother despaired. 'Does it mean that you do not have pots and pans? That you're only eating take-away? That you do not cook?'

When I turned around, my mum was shoving a frying pan in my suitcase, exclaiming, 'Take this with you!' I said, 'Mum, I can buy a pan in America too!'

But the difference between what I was used to at home in Tokyo and in my New York life went beyond home-cooked versus take-away and microwaved meals. From childhood, Japanese people are accustomed to eating portions that are a third or even half smaller than American portions. And while Americans often eat until they feel completely satiated (or beyond), there is a Japanese mother's saying that recommends, 'Hara hachi bunme' - or 'Eat until you are 80 per cent full.'

In Japan, food is meant to be eaten slowly and every bite should be savoured. But here's the beautiful part - after a good Japanese-style home-cooked meal, you shouldn't feel hungry at all!

The basic foundations of Japanese home-cooked food presentation are:

• Never completely fill up the plates
• Never serve a big portion of any item
• Each item is served in its own dish
• Less is always more
• Each item is arranged to showcase its natural beauty
• Food should be garnished and dressed - lightly
• Fresh is best

Japanese Women Don't Get Old Or Fat, by Naomi Moriyama and William Doyle, published by Vermillion, is available to buy from www.rbooks.co.uk