In French you use the partitive "de" when ordering food, eating food, taking food, etc. Je mange de la soupe. ( I eat soup) Le matin je bois du jus d'orange et je mange des tartines avec de la confiture. Generally you use de plus the definite article (de la , de'l, du, or des) when speaking of food, and it may be translated as "some" or simply left untranslated. You use the partitive because you're talking about an undetermined quantity of la soupe, le jus, les tartines, la confiture. Pour le dejeuner, je desire du poulet et Jean desire de la salade. Comme boisson Jean choisit de l'eau minerale, moi, du vin rouge. Nous maneons des fruits comme dessert. (Forgive the lack of accents, I don't know how to make them on my computer.) But with verbs of liking or disliking you use the definitive article when discussing food. "J'adore le chocolat; je deteste le nougat". And that's because you like or hate the whole entity called chocolat or nougat. So the French use le, la, les. In English we often don't distinguish the difference. I eat chicken because I love chicken. In French, je mange du poulet parce que j'adore le poulet.
And that's why the English "We are eating the food" bothers me. We're eating the food Aunt Mary brought over. We're eating the food leftover from Thanksgiving, ok! But just "we are eating the food" is not good English and that's why I translated the English into Nous mangeons de la nourriture. You're not eating all the food in the world, only an undetermined quantity of food. Nous mangeons la nourriture is not good French.
Because it's "la", it's definite. "Nous mangeons la nourriture" is very weird in French, but it means what it means, it's a definite food. It has to be also "a" definite "food" in English.
The common sentence is "Nous mangeons de la nourriture" (even if the redundancy is very weird and awkward in French) = We eat (some) food. Here, it's not definite food.
Actually "nous mangeons de la nourriture" is correct. Because "du" here is actually the sum of "de" and "le". And since there's no word for "de" + "la" and since the word "nourriture" is feminine, using "de la" would be the way to say "we're eating (some) food" or "we eat some food".
BTW, If you're translating from french, you could chose not to use the word "some" because it's understood