French MPs have adopted a bill aimed at banning the use of fashion models deemed to be "excessively thin".
Models will need a doctor's certificate that their health is "compatible with the practise of the profession".
Employers who break the law could face up to six months in jail and a €75,000 fine (£54,000, $81,000).
A previous version of the bill had suggested a minimum Body Mass Index (BMI) for models, prompting protests from modelling agencies in France.
But the final draft approved on Thursday allows doctors to decide whether a model is too thin by taking into account their weight, age, and body shape.
It also says that digitally altered images making a model's silhouette "narrower or wider" should be labelled "touched up".
France is not the first country to legislate on underweight models - Italy, Spain and Israel have all done so.
Anorexia affects between 30,000 to 40,000 people in France, 90% of whom are women.