Rich in vegetables, fruits, cereals and extra virgin olive oil, the Mediterranean diet is based on a moderate consumption of fish, eggs, red wine, and a small amount of meat.[Photo provided to China Daily]

And it's the same in Greece, says Antonia Trichopoulou from the Hellenic Health Foundation. Unsurprisingly, over 65-year-olds are the best at eating traditional dishes, while the youngest generations have succumbed to the lure of fast food.

"The decline has various causes. We are witnessing a globalization of eating habits, with (the spread of) the 'Western diet'", said Serra-Majem, pointing a finger of blame at the growth of the tourism sector in particular.

It has been more marked in coastal areas, particularly in Spain or on Italy's Adriatic coast.

"Uncontrolled tourism leads to high urbanization and... increased consumption of meat, refined flours and a reduction of the traditional diet," he said.

Oranges in Ibiza

The change in eating habits is having a significant impact on public health with the rise of obesity, cancer, cardiovascular disease and diabetes among populations previously known for their longevity.

Seven in 10 Greek adults are now overweight or obese, and about 11 percent have diabetes, according to Trichopoulou.

The Mediterranean diet combined with physical activity could prevent many diabetes cases, said Serra-Majem.

While some regions are doing better at resisting fast food－such as southern Italy and northern Africa－the race is on to find a way to slow or reverse the diet's decline, with the meeting in Milan just one such bid to save it.

As well as the health fallout and associated medical costs, dropping the diet also has an impact on the environment since "almost 25 percent of greenhouse gas emissions come from food production," he said.