Is there a word for one who enjoys to eat for the sake of eating (a food hedonist)?
"Foodie" is a more informal term.
From Wikipedia: "A foodie is a gourmet, or a person who has an ardent or refined interest in food and alcoholic beverages. A foodie seeks new food experiences as a hobby rather than simply eating out of convenience or hunger."
Gourmand, gourmet and epicure appear to match what you're after, as perhaps does food connoisseur.