"I eat the sugar."
when you get "I eat sugar", which means an undefined quantity of sugar, translated in French by the partitive construction with preposition de+ definite article:
je mange du sucre (du = contraction of de+le)
je mange de la soupe
Not all words ending in -e are feminine. Genders are not determined by the actual form of the word, although there are a number of patterns you might find useful: http://french.about.com/od/grammar/a/genderpatterns.htm