Saving leftovers from restaurants in Paris

I live in Paris in France, and I never saw anyone doing that, so I'll advise you to avoid it, because you'll probably create quite an awkward atmosphere, even in a "not very classy" restaurant.

Don't even try it, it may send an already obnoxious Parisien waiter over the edge. He'll likely pretend to not understand what you're saying.

European portion sizes tend to be manageable for most normal people unless you go to an American themed 'restaurant' that engages in the likes of rib eating competitions.

The concept of ”doggy bag“ doesn't exist in most of Europe. It's a North American thing. Why would a restaurant provide boxes for people to take food home? Restaurants serve food for eating on the premises. Furthermore portions in France are typically a lot smaller than in the US, for a number of reasons: people are smaller on average; you aren't supposed to have food left over; quality over quantity; you're supposed to have room left for desert.

France doesn't even have a word for “doggy bag”. Québec as emporte-restes, but if you use this term in France you'll probably get a blank look. Since a few years ago, the government has tried to promote “gourmet bag”, with little success. The practice is neither popular with French restaurant owners (yet another constraint, and will people now expect to get bigger portions so that they have leftovers?) nor with French restaurant goers (if I go to a restaurant, it isn't to get leftovers).

This is slowly changing, however. Even though the concept isn't very popular, it's at least becoming known. Furthermore it's getting more traction because it's environment-friendly at negligible cost. It should become a lot more widespread over the next few years because starting on July 1st, 2021, restaurants will have to provide doggy bags by law. Until then, you can ask the waiter, explain if necessary, and they may or may not accommodate you.

It can happens, but most of the time, the waiter (or more probably the owner) will propose it to you.
Tell them it was very good (they will ask), but it is a shame that you are stuff and can't finish.
If it's possible, they should get the meaning, and propose it to you.

It happens multiple times with my parents. My parents even got some bones for the dog (the real doggy bag^^).
It happens mostly in independent, family-owned restaurant.
Additionally, i don't think I remember it happens in Paris, or in big cities, it was more frequently in country restaurant.
It never happened in Branded restaurant.

My advice : feel it before asking.
If you have a good feeling with the Waiter, the owner, if they are not overbooked, if you talked with them (in french, in their native language, or in your own language if they seems fluent in it).
if you make them laugh, if you learn about them and if they learn about you/your country.
Basically, if you befriend them, you can go (and yes, it is "allowed" to "befriend" the waiter/owner of a restaurant in France, that's the French spirit).

PS : for obvious reason it is FORBIDDEN in all-you-can-it buffet (and yet, I'm sure you can get it in reasonable amount if done properly).

I just tried asking for a box in a pizza and tapas restaurant in La Plagne, France. It was no problem at all, worked just like in the US. They brought me a pizza box for the leftover pizza. Maybe this is different than other places in France because La Plagne gets a lot of tourists -- but it's never unreasonable to ask to take food with you that you paid for. You can ask, they will figure it out.

Honestly I don't think it's so uncommon to ask for a doggy bag also in Europe, in my case in Italy.

I saw it a lot of times, and no problem at all for the restaurant to give you a box for the food you paid for and that will be garbage anyway. Usually the portions are smaller than in the US, so less likely you will ask for a doggy bag, but if that's the case I don't see any problem in asking for it.