By now, most of us are aware that there is an obesity epidemic in the world. If not carrying a paunch and a double chin of our own, the majority of us have a brother, a mother, a neighbour or a colleague who does. Most of us also realise that it’s a growing problem, maybe even an alarming one, and that something needs to be done.

When one lands at the Casale airport in Brindisi, Italy, these worldly problems seem far removed. Already from the taxiing aircraft’s windows one can see not only a sparkling sea, but olive groves and vineyards. The “toxic environment” that obesity researchers have begun to talk about - where all of us, young and old, are likely to get fat - feels like a bad dream from a different, harsher, more Anglo-Saxon world. After all, this is the southern part of Puglia, the sun-drenched and beach-lined heel of the Italian boot, the place that food and travel magazines have been in fierce competition to dub “the next Tuscany” (or Umbria, for those who are picky about these things). It’s a place where the Mediterranean diet has reigned for centuries, where oranges are harvested in the dead of winter, and where the landscape is dominated by phalanxes of secolari - majestic olive trees, hundreds of years old. There are no strip malls and no fried foods in sight.

Unfortunately, Puglia is in a part of Europe - one stretching from Spain in the west to Cyprus in the east - that is experiencing one of the most curious and alarming developments in the global spread of obesity. It is here, in the land of the Mediterranean diet, that the numbers of overweight and obese children are beginning to reach truly epidemic proportions. And southern Italy is the hardest-hit region of all.

A local paediatrician, Margherita Caroli, is one of Italy’s foremost experts on childhood obesity. This strong, determined woman of 51, with a sharp nose and an easy laugh, was born and bred in southern Puglia. Few people have observed the obesity problem at such close quarters and what she has seen, and continues to see, worries her deeply.

”If we don’t do anything about this, it will keep on growing,” she says. “We will have a country where obesity is the norm. It will be a country of sick people.”

Recent research bears this out. A study published in Obesity Reviews in 2004, which detailed data collected by the International Obesity Task Force (IOTF) from across Europe, shows the prevalence of overweight and obese children among those aged seven to 11. In northern Europe, the numbers vary between 10 per cent in Russia and 20 per cent in the UK. These figures are worrying in and of themselves, but compared with the south they seem almost inconsequential. In southern Europe, the numbers range from 27 per cent in Cyprus to 31 per cent in Greece, 34 per cent in Spain, 35 per cent in Malta - and 36 per cent in Italy.

”This is a completely new phenomenon,” says Professor Philip James, the chairman of the IOTF. “And we now have data showing how it is accelerating, with an upward spike in the past few years, implying that it is getting totally out of hand. As far as we can understand, the human race has never witnessed anything like this before. It’s quite extraordinary.”

The definitions vary, but the IOTF defines overweight and obesity with the help of Body Mass Index, which measures body fat based on height and weight. BMI cut-off points depend on the age of the child; for example, among eight-year-olds the cut-offs are BMIs of about 18.4 for overweight and 21.6 for obesity, for 14-year-olds about 23 and 28 respectively.

For a child, being overweight and obese is a problem that goes far beyond the risk of being taunted, or huffing and puffing when climbing stairs. It is the direct cause of a series of ailments more commonly associated with smoking, drinking and gorging grown-ups: hypertension, sleep apnoea (breathing difficulties), depression, poor glucose tolerance and, above all, the insidious Type 2 diabetes.

”When I was a medical student, I knew old people got it,” says James, referring to the disease still commonly known as “maturity onset diabetes”. “But kids? It’s crazy. It’s a catastrophic problem.”

Equally serious is what happens to these children when they grow up. Studies have shown that as many as 40 per cent of overweight children stay overweight when they pass into adulthood. And as they do, they carry with them a greatly increased risk of heart disease, colon cancer, stroke, breast cancer, gall bladder disease and endocrine disorders. In other words, they run a big risk of becoming patients for life - and, as such, increasing the pressure on the health system.

The curious thing about Italy in all this is that, in some ways, it remains the country of the bella figura. Italian adults are among the slimmest in Europe, confirming the impression one gets when travelling on the underground in Milan or strolling into a 19th century coffee bar in Rome - people are generally fashionable, flirtatious and fit. Although the rates of overweight and obese people are rising among Italian adults, just as they are among all Europeans, the numbers are still much lower than, say, those in the UK - or in Greece, for that matter.

But for children the situation is the opposite, as the IOTF data show. And as with so many other lifestyle factors in Italy, there is a deep north-south divide. Eight-year-olds in the richer, northern part of Italy are overweight to about the same extent as their peers in Sweden or Belgium. In the south, however, a recent study shows a prevalence of 45 per cent, with some parts - such as Campania, the region where the US physiologist Ancel Keys dreamed up the term “Mediterranean diet” - reaching levels as high as 55 per cent. These numbers are identical to those from the hardest-hit parts of the US.

”The problem will explode,” says Antonio D’Amore, a researcher at the Italian Institute of Health in Rome. “When it explodes, it will be much worse here than in other European countries.”

Deep in the historical centre of Francavilla Fontana, a mid-sized town 35km west of Brindisi, stands an orange, two-storey building from the 1940s. The Scuola Elementare Aldo Moro is Margherita Caroli’s alma mater. It is just after 10am and the children, most of whom are between eight and 10 years old, are ready for their mid-morning meal, which for many of them means breakfast.

Just inside the entrance stands the provider of many of those breakfasts: a vending machine selling crisps, biscuits and fizzy drinks. The imposing headmaster, Ignazio Forleo, points to it and says: “Look, it’s already getting empty.”

In the classrooms, the laughing, wide-eyed children are busy unpacking their bounty. Almost all of them have either bags of crisps, packets of crackers or the ever-present Italian merendine, a kind of factory-made sweet pastry, often covered or layered with chocolate or custard. Apart from a few panini, there is scant evidence of any food that shares a single ingredient with the classic Puglian, or Mediterranean, diet.

A decidedly chubby eight-year-old named Dalila is fingering two packets of factory-wrapped, golden yellow merendine cakes. She shyly explains that she chose which mid-morning snack she wanted herself, and that she opted for the merendine because she “likes their lemon flavour”.

Of these children, about a fifth - in one of the classes, as many as five out of 20 - are fat. Caroli, who is showing me around, says they are almost without doubt clinically obese, and guesses that at least the same number are overweight.

These children are as innocent as they come. They have little attitude towards the food they’re about to eat. But they also seem to lack any understanding of what is good or bad for them. Almost no one brings fruit - they say they think the other kids will tease them if they do. They also say they don’t like it. In one class the mention of fruit elicits laughter and shouts of “Francesco!” Fingers point to a lonely kid who admits to not minding fruit when his mother makes him bring it. The teachers say that they try to make the children bring healthier food and that they’ve banned French fries, but their struggle is definitely uphill. After a few classes, Caroli is visibly taken aback. “I can’t take it any more,” she says. “It makes me so sad.”

The children also display another disturbing habit: the rejection of the regular meal-time rhythm. Half of them haven’t had any breakfast - most of them never do. Some researchers see this as the most serious problem of all. “A big mid-morning snack means they’re not hungry at one, when they’re supposed to eat lunch,” says Amleto d’Amicis, a leading government nutritionist. “When they get out of school at four, without having had lunch, they see their mother and the first thing they say is that they haven’t eaten. So the mother takes them to a pizza place or to buy something else. This means that when dinner arrives - with maybe even vegetables - again, they’re not hungry. And so when they’re about to go to bed their mother gives them a glass of milk with four biscuits.”

When we get back to the entrance of the school, two girls are waiting for the caretaker to put their money in the machine so that they can get their crisps. Forleo explains that many parents leave money with the caretaker when they drop off the kids in the morning and instruct him to buy what the kids ask for when it’s time for the snack. After the girls have left we take a look at the machine; even the bags of crisps and packages of biscuits that were there 15 minutes ago have now gone.

”There used to be a way of thinking about food that’s been lost,” Caroli says after our visit to the school. “Food was the roots of the family. Instead it has become a status symbol. For many, it’s a sign of being rich to be able to eat anything you want.”

This doesn’t mean that the Mediterranean diet is dead or has disappeared, she says. Children still eat pasta, olive oil and even the occasional vegetable. But they do this less regularly, and they mix it with other things that until now have had no place in the southern Italian diet: salty snacks, fatty fast food, and the ever-present sugar-laden merendine. Fruit, ever abundant in this part of the world, has come to be considered a poor man’s food.

Caroli works from the Ospedale Generale D. Camberlingo, off a pot-holed road on the outskirts of Francavilla Fontana. A boxy, dreary building, it consists of three rather grey, dilapidated rooms; her main weapons are a well-worn scale, a stadiometer for measuring height, and her three assistants, one of whom works unpaid. But what Caroli does here is unique. Not only do she and her staff spend a great deal of time collecting and computing data that are presented at high-level international conferences and published in prestigious peer-reviewed journals; they also do the heavy, day-to-day work of treating obese patients and implementing prevention measures in the surrounding communities. This gives Caroli, a woman who almost bursts with energy, an on-the-ground understanding of the problem that is rare in the higher stratospheres of the scientific community.

Apart from the food, she says, the main problem for children in southern Italy today is that they move too little. Much too little.

”They only do two hours of gym class each week,” Caroli says. “If the parents are rich, they can take the children to do sports. But if they’re poor... there are very few free activities available.”

The Palombieris are one of the families that have come to Caroli’s clinic for help. They live in Oria, a town a few kilometres to the south-east of Francavilla. They are there - the father Mimmo, 33, mother Patrizia, 30, and their two sons, Damiano, seven, and Mattia, a 15-month-old toddler - because Damiano is about 10kg overweight. He’s a boy with shy, dark eyes, and even if he’s clearly round, he has not yet reached the stage where he has difficulty moving.

”They tease me at school,” he says, looking at his hands. “They call me bloaty, fatty bomb. So now I want to lose weight.”

Mimmo and Patrizia explain that Damiano has a penchant for McDonald’s, French fries, mayonnaise and merendine. He also spends too much time in front of the television.

”We have no green spaces, so he can’t go out,” says his father. “The communal park is on the other side of town, and often it’s closed anyway.”

Mimmo does two jobs to make ends meet: in a military shipyard during the day and installing air conditioners in the evenings. Often he comes home after 10pm. Since the family has only one car - and since life in Oria, as in almost all southern Italian towns these days, is built around having a car - this means Patrizia rarely ventures outdoors with her son.

”But today we went for a walk to the city centre,” she says. “He was very proud of himself!”

Apart from helping children like Damiano - whom she says is a relatively easy case, since he’s well motivated and has a loving family to help him - Caroli tries to implement programmes for better food in schools, and access to more physical activity in the towns that fall within Brindisi province. She says the only way to stem the “tidal wave” of childhood obesity, as Philip James at the IOTF calls it, is to work with preventive measures.

”Trying to treat every child is like trying to empty the ocean with a spoon,” she says.

This preventive work means meeting the mayor of Oria to see if the municipality can adopt a programme to let the children walk to school together, while being watched over by adults (the mayor was, after a heated discussion about the weight of the children’s backpacks, ready to implement the scheme). It also means changing the menu at local schools to traditional Puglian food made from fresh produce - at one school we visited, the children were happily tucking into orecchiette (pasta with boiled greens). But Caroli still runs into frequent resistance from local authorities - often for economic reasons - and from central government, where recognition of the problem is, she complains, much too slow. Sometimes even the parents complain, as they did in Brindisi in 1999 when Caroli changed the menu in one of the city’s schools. “Our Children Starve from the Diet,” screamed the headline in a local paper.

”It is an uphill struggle,” she admits. “And in the end, the people have to do it themselves. I can’t make them healthy. I can only offer them the means to get healthy.”

In some ways, what is occurring in southern Italy today is simple. “Calories in, calories out”, as they say in the world of nutrition. It’s the same all over the world: people eating energy-dense foods while not doing enough moving around to use it all up. This makes them fat.

At the same time, scratching the surface a little, it is equally clear that the severity of the childhood obesity pandemic has causes unique to this region. Italy, albeit in common with some other southern European countries, has lax regulation of television commercials. All channels, from the three run by the state to the four main private stations (three of which are owned by prime minister Silvio Berlusconi), are flooding Italian living rooms with adverts using every possible means to sell more or less unhealthy food to children.

Maria D’Alessio, a professor of child psychology at Rome’s Sapienza University, recently carried out a study of commercials directed at children. She was shocked by the results. “It is almost as if our television is specialising in selling food,” she says. “We might as well be saying to our kids that they only are worth something when they eat.”

Italy has also gone through a peculiar kind of modernisation. While most of its society has embraced the materialistic aspects of any industrialised country, the central role of the mother - the almost mythical mamma - means that while women are now supposed to go out and work hard, they are still expected to take sole responsibility for the welfare of the children. Which, of course, doesn’t add up. Instead, the mothers often compensate by giving in to everything their children ask for.

There are other reasons for the rise in obesity: the cultural propensity towards seeing fatness as a sign of health; a relatively quick historical shift from scarcity to abundance; and the strong influence of US culture following the occupation of the south during the second world war.

But these peculiarities aside, perhaps the most urgent aspect of what is happening in Italy is what it tells us more generally about the state of the obesity epidemic today. Our first impression at the Brindisi airport made clear that Puglia isn’t the US; yet the kids in southern Italy are visibly, seriously fat. This means we have to shed the common image of what is a “toxic”, “obesogenic” environment. People no longer only get fat by shoving hamburgers and sugary soft drinks down their throats. In other words, the opening of another McDonald’s isn’t the only cause for concern (in fact, France, where there are three times as many McDonald’s as in Italy, has a much less urgent problem with childhood obesity).

Rather, children get fat when a complex series of factors act together to make them so: changing food habits, of course, but also family structures, traffic, city planning, criminality and economic welfare. And southern Italy shows us that when these factors are aligned, no tradition, no self-image and no climate in the world can keep the fat away.

Caroli believes, as do most of her peers, that the only thing that could hold back the fat is a massive campaign, led by the state - and, in the case of Europe, by the EU - involving families, schools, municipalities, the food industry and media. She’s a bit sceptical it will happen any time soon, but she keeps her hopes up. As Caroli’s Greek colleague Anthony Kafatos puts it, watching the epidemic unfold from his university office in Heraklion, Crete: “We need to do what we did with the Olympics - really come together to make it successful,” he says. “Otherwise, forget about it. We are lost.”