By Pascale Harter
BBC Radio 4's Crossing Continents
As Mauritanian nomads drift to the city, modern life is beginning to challenge one of their most cherished traditions - the force-feeding of young girls.
Under a patchwork tent in Kiffa, on the western edge of the Sahara desert, a nomadic woman called Braika crossed two sticks around my ankles and squeezed the ends together with rope until I yelped in pain.
Mauritanian women work hard to fatten up their daughters
She was showing me how she forced her daughters to swallow litres of milk and mountains of couscous for days on end until they developed wings of fat hanging from their arms and their skin was traced with silvery stretch-marks - attributes considered the height of feminine beauty in Mauritania.
"They eat and eat, and drink and drink, and when they can't eat anymore we pinch them and sometimes they vomit," Braika said.
"When they vomit on purpose, we make them eat the vomit to teach them not to do it again."
Braika proudly wobbled her flabby arms and showed off her own stretch-marks.
She did not feel guilty about force-feeding her daughter.
She assured me that once the ordeal was over the girls were grateful, because nicely fattened up they could take their pick of husbands.
"A thin girl could be blown away in the wind, people think she is a stick and she will never find a husband," she said.
Nomads believe a fat girl is a healthy girl.
But in reality, obesity has reached epidemic proportions among Mauritanian women and it is killing them.
Barely into their 40s, fattened women are dying from obesity-related diseases such as diabetes and heart failure.
Mounina has worked to warn women of the dangers of obesity
Mounina Mint Abdalla is a health consultant who worked for years with the government trying to stamp out force-feeding.
But she acknowledged that government radio sketches warning women of the dangers of obesity have had little effect on a society where fatness is revered as a symbol of nobility and good breeding.
Nonetheless, force-feeding and the nomadic way of life is fast disappearing, said Mounina.
"The country has been hit by years of drought and we simply don't have that kind of quantity of milk now, or the time it takes," she added.
Zeid, a nomad in the market town of Aleg, said he was thinking of trading his last remaining goats and camels for a passage to the city.
"We are in deep crisis," he said.
"The price of the food is becoming so high, that we can't afford to feed ourselves, and for this reason we cannot feed the animals.
"The only thing we can do is move to the city."
In the market in the capital Nouakchott, Mounina pointed to all the women working in the stalls selling everything from brightly coloured veils to fake Chanel sunglasses.
Women come to the market to buy steroids for their daughters
"Just 15 years ago, women didn't work at all but now all these women are working because life in the city is very expensive," she said.
But despite this, women are still finding ways of fattening themselves up.
A pill-seller said he could not count the number of women who buy steroids meant for cattle.
"Some come and buy 20 boxes in one go," he said.
But if force-feeding creates problems for women in later life, the cattle steroids can be an instant killer.
Side-effects include renal failure and heart attacks.
Dr Maagouiya, the general surgeon at Nouakchott's main hospital said that without autopsies - which are not permitted in Mauritania - he cannot be sure how many lives the steroids have claimed but he believes the figure is high.
Yet mothers still come to him to request pills for their daughters, believing that thin girls are shameful because they look "sick".
They tell me that if they lose weight their husbands will leave them
Dr Maagouiya, general surgeon
To be "sick" is often a euphemism for having HIV/Aids in Africa.
The message is getting through to some Mauritanian women, like Mounina's nieces who have started exercising around the stadium as the sun goes down.
But they seemed to be doing it reluctantly and said they were trying to lose weight purely for health reasons, not because it would make them more attractive.
Dr Mougiya said he encounters the same attitude when he holds seminars trying to persuade obese women to slim down.
"They tell me that if they lose weight their husbands will leave them because everyone knows that in Mauritania men prefer a fat woman."
One thing is finally beginning to shake up popular attitudes to fatness - the explosion of Arab satellite channels obliterating the monopoly held until recently by the state channel.
Mounina's daughters are inspired by the slim stars of satellite television
It was a big moment in Mounina's house when I visited - it was the final of Star Academy, the talent music show by the Lebanese music channel LBC.
Mounina's teenage daughters told me they do not want to be fat like their cousins who are only a few years older then them.
They said they want to be "a normal size" like the Lebanese pop stars.
"Now Mauritanian men are looking at Lebanese singers and starting to compare them with us," said 19-year-old Aicha.
"They look at their wives and say 'why aren't you like those singers?' There are some who've got divorced because of those Lebanese singers.
"The men say to their wives 'why are you fat, why aren't you like Britney Spears?"
The lifestyle in Mauritania is changing fast - donkey carts and fruit stalls in Nouakchott are giving way to fast-food restaurants.
In "Burger Hot" I met a group of men who were not sure that Mauritania's love affair with thin men and fat women is completely over.
"If you're an overweight man, women make jokes about you. They say that you look like a woman.
"But if you tell them to lose weight they don't believe you.
"They say you are out of your mind, that you are trying to trick them because they know men here don't like thin ladies."
But another man said that no matter how many images of slimmer women are beamed into Mauritanian living rooms, former nomads are too set in their ways to ever fully accept a foreign standard of beauty.
BBC Radio 4's Crossing Continents was broadcast on Thursday, 26 April 2007 at 1102 BST.