Unfortunately, neither the CCC, Catechism of Pius X, or Catechism of Trent define gluttony. The Baltimore Catechism simply defines it as an excessive desire for food or drink. Fr. Hardon’s Catholic Dictionary has probably the most helpful entry:
Inordinate desire for the pleasure connected with food or drink. This desire may become sinful in various ways: by eating or drinking far more than a person needs to maintain bodily strength; by glutting one’s taste for certain kinds of food with known detriment to health; by indulging the appetite for exquisite food or drink, especially when these are beyond one’s ability to afford a luxurious diet; by eating or drinking too avidly, i.e., ravenously; by consuming alcoholic beverages to the point of losing full control on one’s reasoning powers. Intoxication that ends in complete loss of reason is a mortal sin if brought on without justification, e.g., for medical reasons. (Etym. Latin glutire, to devour.)
So we’ve dismissed “dainty,” but now the question is: what is “exquisite” food and drink? Sounds like that special anniversary dinner at the French restaurant could be morally problematic. Applebee’s instead? Fish & chips but no lobster? Gallo but not Mouton-Rothschild? If a moralist is going to use a term, wish some type of definition or guideline would be given.