There are two stereotypes that typify the German nation in the British mind; the first is the sun-lounger hogging German abroad; the second is the German nudist at home. At least one of these stereotypes is set to be dramatically blown apart over the coming years, at least that's according to the findings of the German Free Body Culture movement (FKK), the official representitive body for Germany's infamous naturalists.

The FKK gained popularity (especially in East Germany) during the Cold War period where it offered an attractive social alternative to the communist party organisations. At its peak in the 1980s the BBC estimated that over 50 million Europeans enjoyed naturist holidays. More than 20 years on, there are still 50,000 registered nudists in Germany whilst up to 7 million Germans enjoy sunbathing naked. Healthy statistics? Not so, says Kurt Fischer, president of the German FKK Association - "The numbers are falling by about 2% each year".

Fischer lays the blame for this firmly at the feet of Germany's declining birth rate and increasing reliance on immigrants to fill the population void. In 2010, government statistics revealed that only 8.2 children were being born for every 1,000 citizens, the lowest birth rate in Europe. But the trend is nothing new, Germany's birth rate has been steadily declining since the 1970s and in order to maintain a steady population of 85 millions (essential for caring for an ageing population), Germany will need to welcome 32 million foreigners by 2050.

And these foreigners? It turns out they're not so hot on nudism. In Fischer's view "many immigrants come from countries with strong religious beliefs" that mean "they just aren't into FKK." These immigrants include a swelling Muslim population as well as a conservative Eastern European faction who see public nudity as obscene rather than the wholesome and natural image the FKK promotes.

In America, a similar pattern is emerging. Statistics gathered between 2006 and 2008 on the ClothesFree Forum revealed an ageing American nudist population. The average age for this period was 46-49 years old - approximately 52-55 years old in 2011 - whilst the number of members fell by 10'000 between 1990-2000.

The trend looks set to continue as nudity is increasingly sexualised by the media and society becomes more sceptical about a minority who enjoy public nudity. Historically - especially in Germany - nudism has been seen largely as a family activity with camps and activity groups set up for full family participation. Cultural changes in the media now make it more difficult for nudists to be accepted without being labelled as perverts or weirdoes. Single men have been chased off and the younger generation have been put off by a pursuit they see as largely middle-aged.

Perhaps another reason for the decline in nudism is one that rings a little closer to home; we're getting fatter. Following World War Two, Europeans and North Americans have steadily increased in size - we Brits have seen our waists increase by an average of 6.5" over the last 60 years whilst we've only grown an extra 2" in height. Germany is little different; their waists have expanded by an average 1.57 inches from 1994-2004 and as they've added to the scales they've shed pounds in confidence. The result? More people are covering up.

As we stride through the peak of the naturalist season, it seems like the nudist is more endangered than ever - so spare a thought for them as they literally bare all in an attempt to draw support for their dwindling lifestyle.

Interested in finding out more about British Naturalism? Click here, "nothing's better!"