The "how thin is too thin?" debate has been raging in the fashion industry for many years, but now it looks like one of the style capitals of the world is finally taking a move in the right direction.

A new law has been proposed in France to ban models from the catwalks if they are deemed to be unhealthily thin. The new legislation, proposed yesterday, would require modelling agencies to get medical certificates for each model proving their BMI is over 18.

Regular weight checks would also be required.

BMI, or Body Mass Index, gives an idea of a person's body fat based on their weight and height. A healthy BMI is deemed to be anywhere between 18.5 and 24.9, with anything under that considered underweight and anything over that considered overweight.

For a standard 5' 8" model, any weight below 119 lbs (8.5 stone) would be considered underweight and would be banned from modelling in France under the proposed rules.

The news comes just weeks after the Danish magazine Cover came under fire for using an extremely thin model in one of their photo shoots – something the magazine's publisher has since apologised for. 

Dr. Olivier Veran, the French lawmaker who wants to introduce the new measures, says that there is a worrying trend of modelling agencies encouraging models to be as thin as possible. "We want to combat the idea that an agency could urge a model to stop eating; for example eating cotton balls to lose their appetite, to always lose more weight," he said.

"We have had chief editors of prestigious magazines tell us that more and more often, they are obliged to use Photoshop, not to make the models look slimmer," he said, "but to erase the tracks of bones under the skin, to make them look bigger."

France is not the first country to consider bringing in such measures – Spain, Italy and Israel already have similar laws in place.