Weight-watchers everywhere can breathe a sigh of relief. Contrary to their image as slim models of restraint, French women, it seems, really do get fat.

According to a 2009 study published on Tuesday, 15.1% of France's women are classed as clinically obese, while a further 26% are overweight.

The survey, conducted by TNS Sofres Healthcare and Swiss pharmaceuticals company Roche, also pointed to similar trends among the male population, with 13.9% of Frenchmen obese and 38.5% overweight.

The world has long marvelled at the ability of the French population, and particularly its women, to remain thin in a country famed for its pastries, cheese and wine.

French author Mireille Guilano even published a diet manual in 2004 entitled "French Women Don't Get Fat", praising the eating habits of women who prefer to savour their food calmly and never snack between meals.

But the reality is that over the past 12 years, the average French person has put on 3.1 kg (6.83 lb) and added a further 4.7 cm (1.85 inches) around the waist, the survey showed.

Doctor Marie-Aline Charles, who helped conduct the research, said urban lifestyles were largely to blame.

"Obesity rates have really risen sharply in urban areas where there's a concentration of sedentary jobs, public transport, less need to walk and a much greater availability of food," she told Reuters in a telephone interview.

However, other countries, especially the United States, were faring worse, she said.

"We're currently seeing in France the same levels of obesity as in the United States in the 1970s, so we're about 40 years behind," she said.

According to latest data released by the World Health Organisation (WHO) some 31.1% of U.S. men were classified as obese and 33.2% of women.

The TNS Sofres Healthcare survey was based on replies from 25,286 people during the course of the year.