ROME (AFP) - Eating a Mediterranean diet has long been a byword for healthy living, but the very people who coined it are straying from sun-kissed fruits and legumes and their waistlines are paying the price.

The region is undergoing a "nutrition transition" from traditional, sustainable foods towards more meat and dairy products, a new report by the UN and International Centre for Advanced Mediterranean Agronomic Studies said on Thursday.

The bottom line is that many in southern Mediterranean countries, from Egypt to Lebanon, Morocco and Turkey, are piling on the kilos, struggling increasingly with obesity and chronic diet-based diseases, the UN's Food and Agriculture Organisation (FAO) said.

"Globalisation, food marketing and changing lifestyles - including changes in the roles women play in society - are altering consumption patterns in the Mediterranean," the report said.

The famous diet is based on cereals, vegetables, pulses and a moderate intake of fish and meat, but tourism, urban development, depletion of natural resources and a loss of traditional knowledge are altering the menu.

Products are being increasingly sourced from outside the region - only 10 per cent of the local crop varieties cultivated in the past are still grown today - which affects not only local food producers but also the environment.

"The Mediterranean diet is nutritious, integrated in local cultures, environmentally sustainable and it supports local economies," said Alexandre Meybeck, coordinator of the FAO's Sustainable Food Systems Programme.

"This is why it's essential that we continue to promote and support it," he said.