I end up facing this situation all the time with Granny. She doesn't finish all her food on the plate. I can't save it in the fridge till the next day because then the food becomes hard when you reheat it and she can't eat it hard. So I throw the food away. Is that a sin?

 This is another way in which the poor are richly blessed. It's hard to over eat or over indulge when you're struggling just to eat in the first place.

 

A mortal sin must follow three conditions in order to be one:

1) it must be serious/grave

2) you must know it is a grave sin

3) you must fully consent to it

If any of those conditions are absent, then it is not mortal.

Thus, eating a few bites too much on accident is one thing, and gorging one's self on purpose is another, especially if it's a habit. The few extera bites probably won't do your body much harm (unless perhaps you do it every time you eat). To stuff yourself, I understand, is very bad for your health all around. Therefore it is serious (the destruction of your health), and if you do it knowing it's serious and you do it intentionally, then it would probably be mortal.

The Catholic Encyclopedia quote above suggests that food is neither good nor bad - but surely it must be good in that it is necessary for man to attain his final cause - the beatific vision.

Also, what about great chefs who produce works of art in their food preparation?  I always try to achieve perfection when cooking - to use the freshest and most flavorsome ingredients, to cook them to perfection using a variety of methods (some which can be extremely time consuming), and to present the result in a beautiful way on the plate.

I don't see how that can be a bad thing - it seems rather to be a good thing.

Also, the great chefs of the 18th century cooked enormous amounts of food for banquets (much of which was merely decorative) - was this gluttony?  Do keep in mind that much of the left over food fed the workers in the kitchen or was given away at the gates to the poor.

I end up facing this situation all the time with Granny. She doesn't finish all her food on the plate. I can't save it in the fridge till the next day because then the food becomes hard when you reheat it and she can't eat it hard. So I throw the food away. Is that a sin?

No, would try to give it to the dog or cat if you have one....

  I think it was St. Gregory who said that gluttony meant eating too much, too soon, too eagerly or too luxuriously.

Here's the expounding on gluttony by St. Gregory the Great:
http://cathom.blogspot.com/2008/12/seeking-after-sauces-and-seasonings-for.html

Thanks for that link.  I happen to be a foodie (it is my only hobby really) and always try to use the freshest ingredients in my cooking.  Ocassionaly I cook with items that are priced beyond the reach of the average home cook (truffles, caviar, etc.) Do you think those things would be considered gluttonous?

It makes me think about homes - I don't recall who it was that said it, but we must live according to our station in life, thus it is not sinful for a Pope, King, or Bishop to live in an opulent palace, but it would be wrong for a peasant to (a situation we see in millions of homes today in which people - through trying to keep up with the Jones's - live in homes they can ill afford).  

Would we say that food fits into this category as well?  If you can afford caviar and truffles should they not be eaten?  

As for the "seeking after sauces and seasonings" - these things are so commonplace these days that it would be hard to avoid them - we certainly don't need to go seeking them.  Do you think that the comments of St Gregory the great ought to be tempered with the above ideas in mind?

I definitely do suffer from some of the other points on his list - taking food with too much eagerness, and eating before the right time. In fact, it seems that modern fitness instructors even promote the latter as they try to convince people that six meals a day is better than three (the unintended consequence of which - for many people - is that they end up eating six full sized meals instead of six small meals as people don't seem to know how to moderate portion sizes.