Although known for their love of wine, cheese and steak-frites, the French have an uncanny way of remaining rather svelte. So what is their secret and can they continue to shrink from obesity in the face of their ever-growing appetite for fast food and fizzy drinks?
The flagship store of Galeries Lafayette in Paris is 10 storeys high
My first memory of Paris is of arriving for a visit at the age of 11.
The weekend came courtesy of my French aunt Camille, a Parisienne from the tip of her perfect blonde bob to the kitten heels of her Charles Jourdan shoes. She was petite, not much taller than me at the time... and rather slimmer.
She smelt of Chanel No 5, wore French designer clothes and - to my child's eyes - was the ultimate in sophistication.
And she was taking me shopping to Galeries Lafayette, the Paris equivalent of Selfridges.
I was thrilled... until the moment the Parisian shop assistant eyed my English boarding school figure with that unique hauteur that only Parisian shop assistants can muster, and began an animated conversation.
My aunt's grip on her Hermes-style handbag became quite steely and the discussion ended with the words: "well, the English are bigger for their age."
Years of sausage and chips, and bread and butter pudding at school had taken their toll.
Aged 11, I was too big for Paris.
Coffee and cigarettes
All these years on, little has changed.
A fat Parisienne is clearly a crime against nature
"French women don't get fat" was the title of a recent bestseller, written by a svelte - and dare I say smug - French woman, keen to share her secrets of slenderness with the rest of the world.
I read it in a post-Christmas haze of gluttony, lying on the sofa with a box of chocolates, though I did wonder a little why my best friend had given it to me.
From memory, those French women's secrets seemed to involve eating less and running up and down 16 flights of stairs whenever the kilos threatened to pile on.
She did not mention Parisiennes' real secret - living on black coffee and cigarettes - though it is a diet that appears to work for most, along with steely self-discipline.
A fat Parisienne is clearly a crime against nature.
So, this week I found myself sitting in the waiting room of a French nutritionist, whose services of course come courtesy of the French health service.
After three years of living in Paris, I have had enough. Enough of trying to squeeze a British-size bottom onto spindly French cafe chairs, clearly built by a population of Lilliputians to repel the Anglo-Saxon invaders over the coming summer months.
The nutritionist, Francoise L'Hermitte, was surprisingly sympathetic.
She looked horrified as I admitted that I often did not get time to sit down for lunch.
And that I grabbed snacks on the run. And certainly did not take an hour for my main meal. Too much to do, too little time.
"No wonder!" she exclaimed. "You must sit and enjoy your food, look at it and take in what you're eating. And you have to spend a minimum of 20 minutes on each meal."
As she patiently explained, there are good reasons why the US and Britain are both suffering increasingly from obesity.
For her, junk food is not the main culprit, but our way of viewing food or sitting down for proper meals as a waste of valuable time, preferring instead to graze on the run.
Her advice was everything in moderation: two main meals a day, the biggest at lunchtime, and no snacks in between.
Most French may not be quite so disciplined about what they eat, but many do still believe that sitting down twice a day for family meals creates better eating habits in children and healthier adults.
Overweight people will not be such a rare sight in France by 2020
Francoise L'Hermitte's advice was a long lunch, eaten slowly, savouring both the food and the company, advice I now intend to put into practice on a daily basis.
"For France, a meal is a very particular moment in which you can share pleasure," she said.
"From an Anglo-Saxon point of view, food is just fuel to give energy to your muscles and if you take no pleasure in it, you're breaking all the rules of eating, and if you eat at your desk or too fast, your brain doesn't know when you're full."
But what about all those French that I see at lunchtime, pigging out on steak and chips, with lashings of wine, followed by cheese or perhaps a little creme caramel?
Well, there is another explanation and it is not really such a paradox, either.
Researchers in the US once spent months looking into why the French remained so much slimmer than Americans.
After intensive study, they came to a remarkable conclusion.
It was because the French ate less.
Main courses, puddings, even drinks all come in smaller sizes. No super-size portions in Paris... yet.
Fast food invasion
At lunch in a local restaurant the other day I looked around, in those few moments where I was not trying to commune properly with my food.
Fast food eaten on the run is the real Anglo-Saxon invasion they should resist at all costs
All around me, French office workers were focussing on what was on their plates, amid animated conversations, mostly about the food itself.
Yet as we left, the pavements were full of people grabbing a sandwich to eat at their desk.
The queues at fast food restaurants snaked out of the doors.
Guess which country is home to McDonalds' most profitable franchise? Not the US, not Britain, but France - now due to reach US obesity levels by the year 2020.
As France slowly adopts our eating habits, the nation is getting fatter and starting to worry about it, just as we do.
Earlier this year, French schools banned vending machines. Children here, too, are bigger than ever.
Just as the French try to resist the perils of economic globalisation, they are also starting to realise that their old reverence for food - in the right place, at the right time, and in moderation - is something else worth holding on to.
Fast food eaten on the run is the real Anglo-Saxon invasion they should resist at all costs, if the next generation of children is not to suffer agonies of embarrassment at the hands of haughty Parisian shop assistants.
From Our Own Correspondent was broadcast on Saturday, 24 June, 2006 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.