"She is the woman who eats chicken."
Translation:C'est la femme qui mange du poulet.
They're used in different contexts: http://french.about.com/library/weekly/aa032500.htm
I suppose I can't comment on whether or not "elle est la femme" is wrong, but it would fall under "modified noun" in the link above.
Also, here are 2 more resources that say to use "c'est" for introduction of a noun (la femme)
I believe patlaf is right. The clause: "...qui mange du poulet" is modifying "C'est la femme." According to the link from french.about.com provided above, modified nouns fall under the "C'est" structure, whereas unmodified nouns fall under the "Il est" structure."
Ex: Il est avocat (unmodified)
Ex: C'est un bon avocat (modified)
SiteSurf notes a difference between verbs of liking/appreciation, after which nouns take only the article, not de + article, and other verbs required de + article.
I look at it as a question of capability. You can like/appreciate something in an abstract way, so that it includes things like all the chickens in the world, expressed emblematically as a single single metaphor, le poulet .
But you cannot eat a metaphor, nor can you eat all the chickens in the world. You can only eat "some" chicken, even if it's a lot of chicken. "some" is expressed using de + article (except where the noun is preceded by an adjective, then you drop the article, and it's just de.)
Agreed with ho3YXu7q. And take a look at this: "Qui aime le poulet" - who loves chicken (assuming loves to eat cooked chicken, not to take care about living hens). In that constraction it's okay to use "le poulet" since it's a general symbol; "Qui aime manger le poulet" - who loves to eat chicken. More precise, but chicken is a general symbol as in previous option; "Qui mange le poulet" - who eats chi ken. It can mean exactly the same as previos two options and in that case chiken remains the same general idea.
Correct me if I'm wrong, but it is because we are not talking about a specific chicken in this sentence. If it was a very specific chicken that had already been established, then we could use "le poulet," but since the women is just eating chicken, a nonspecific undefined amount of chicken that has never been established, then we would use "du poulet." Hope that helps.
It's not the whole chicken. Unless you're talking about a very, very specific chicken, e.g., "le poulet sur la table", then you're speaking generally about a specific but unmeasured quantity of chicken, i.e., "some chicken", which is expressed using de + article.
When you talk about le used with generalities, those are very broad generalities, which aren't really capable of being contained within "some" quantity. You can't eat a generality, you have to eat "some" of a specific quantity of a generally described thing.
Also, as SiteSurf has explained on many occasions, you don't need to use de with verbs of liking/appreciation. You can appreciate the general qualities of something which you would be incapable of condensing into a "some" quantity.