VALLETTA, Malta >> The Mediterranean has long been known for its mix of sun, sea, fish, nuts and olives, a combination considered an elixir of health and fitness. An entire industry has emerged to promote a Mediterranean diet that promises to unlock the secrets of Greek and Italian islanders who stay active into their 100s.

Then there is Malta.

Throughout the tiny archipelago in the middle of the Mediterranean between Italy and Libya, bulging waistlines are a common sight, spilling over at cafes near the vast battlements from where the islanders’ forebears repelled Ottoman invaders and launched raids on North African ships.

At breakfast, customers line up for pastizzi, diamond-shaped pastries made with butter and lard and stuffed with ricotta-style cheese or mushy peas and often sold at small, family-run shops. Many return at lunch for timpana pies that are crammed with pasta and meat — and plenty of calories. Candy stores stack their window displays with jumbo packs of chocolates and biscuits, some from Britain, the colonial power here until 1964.

Outlets serving jumbo hamburgers do a roaring trade.

“There’s no doubt obesity is the biggest challenge” for this generation and the next, said Chris Fearne, the parliamentary secretary for health in Malta and a Cabinet member in the Labor government.

Islanders reminisce about homemade soups with potatoes dug from their gardens and about a time when seafood was abundant in their diets. Malta was a place where “adults live to an extreme old age” and where people ate a mostly vegetable diet with an occasional meal of fish, Maturin Murray Ballou, a U.S. travel writer, wrote in a book called “The Story of Malta” at the end of the 19th century.

Godfrey Farrugia, 55, a former health minister and the chairman of a parliamentary working group on diabetes, said fish used to be so common that his mother’s freezer was frequently filled to the brim with fish he caught from the shore during his youth. But a combination of overfishing, pollution, warming waters and industrial fish farming in some bays has disturbed the ecosystem near the shoreline and reduced the local catch, he said.

As a result, fish can be expensive and hard to obtain, as can plant-based staples, most of which are brought in from outside Malta (the Maltese import more than 90 percent of what they eat). Even as the country acknowledges its weight and health problems, there is considerable debate about the feasibility of returning to a Mediterranean-style diet rapidly enough to help address record rates of diabetes and other complications.

Americans are still heavier on average than the Maltese, and the populations of some small island states in the South Pacific are heavier still. But in September, Malta, the smallest European Union country by geographical size and population, with 425,000 citizens, pulled ahead of the Czech Republic as its most overweight, according to a report from the World Health Organization. The Maltese, the report said, are more obese than their neighbors in Cyprus, Greece, Spain and Italy.

This month the International Diabetes Federation said Malta had the highest estimated national prevalence of diabetes for people ages 20-79, at nearly 14 percent, of 56 European countries it surveyed. Deaths from some forms of heart disease are more than twice as high compared with the EU average, according to the bloc’s statistics office.

Life expectancy, at 81.9 years, is still longer than the EU average and slightly longer than in Greece. But that is lower than other Mediterranean countries including Italy, Spain and Cyprus, and longevity on Malta could eventually decline as more islanders contract obesity-related diseases at younger ages and die earlier, said Josanne Vassallo, an endocrinologist at the University of Malta Medical School.

The government is trying to combat the crisis with steps like encouraging mothers to breast-feed, a practice shown in some studies to reduce obesity later in life. The government has also slapped restrictions on sugary drinks and fatty foods in schools, and it has obliged schools to measure the body mass index, which gauges fatness, of all children ages 3-16.

But persuading the Maltese to change their eating habits is another matter.

“I can’t come here to have an espresso and not have pastizzi,” said John Azzopardi, 78, finishing up his breakfast with friends at the richly decorated Caffe Cordina on an elegant palazzo in Valletta.

The attachment the Maltese have to their foods was underscored this year when a Maltese tenor, Joseph Calleja, attacked a proposal to limit the quantities of salt in local bread. The government should resist “potentially altering an ancient recipe that is already under siege from mass production and modern machinery,” Calleja wrote on his blog in March.

Apportioning blame for a global phenomenon as complex as obesity is difficult.

Some experts say there may be a biological predisposition toward heaviness. Others emphasize the sedentary lifestyles in Malta, where there are high levels of private car ownership and where people tend to shun walking and cycling even though the main island is only 17 miles long and 9 miles wide.

Some Maltese also have a gluttonous streak.

Across the harbor, Maltese compete to eat burgers the size of dinner plates at the Trees Medieval and XXL Restaurant in Sliema. Andreas Nelles, the German-born owner of the Trees, said he tried several different business models before settling on monster-size portions because “that is what Maltese people like.”

About 40 people had won free meals by consuming the burgers within one hour since the contest began nearly a decade ago, said Nelles, who added that the vast majority of contestants failed and left the restaurant with sizable doggy bags.

Even chefs at comparatively upmarket restaurants say indulgence is commonplace.

Maltese diners will ask, “What the hell is this?” when served a quantity of pasta that would be acceptable to tourists, said Aaron Degabriele, 43, a television chef and the owner of Aaron’s Kitchen, a restaurant. Maltese pasta portions needed to be about 50 percent bigger, he said.

Reinventing Maltese cuisine “is something I have at heart,” said Degabriele, who is among a group of nine candidates studying for a master chef diploma introduced this year by the University of Malta to promote healthier cuisine.

Among the challenges faced by Degabriele, and by ordinary Maltese seeking a better diet, is cost. Apples can be more expensive than pastizzi, and locally caught sea bass is up to three times as expensive as the farmed varieties around Malta that are mostly exported to countries like Italy and Japan.

Dishes like vegetable soup are considered to be “poor man’s fare, which is ironic,” said Claire Sillato Copperstone, 47, a lecturer in food studies and environmental health at the University of Malta.

“We are telling our people to eat a Mediterranean diet, which is possibly not cost-effective for the typical family of four or five people,” Copperstone said.

“Pastizzi is cheap and salad is 5 euros” ($5.45), said Laura Coppini, 21, a health sciences student at the university.

Farrugia, the former health minister, is campaigning to scrap a law that restricts children under 18 from seeking some forms of medical help from family doctors without parental consent. Giving teenagers more confidence to consult with doctors would be “a golden opportunity to tackle lifestyle and preventive diseases” including obesity, he said.

Some parents still encourage their children to overeat, said Malcolm Scicluna, a senior civil servant whose body mass index reached 35 — a level considered obese — before he hired a personal trainer and began a diet and exercise regimen that has enabled him to shed about 33 pounds since September.

“Probably it comes from our history when we were invaded,” said Scicluna, 39. Gorging on food would “make up for the periods of starvation,” he said, “but obviously nowadays that’s not relevant anymore.”

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