In Europe, the attitudes towards taking leftovers from a restaurant can vary depending on the specific country and cultural norms. Generally, it is not as common a practice as it is in some other parts of the world, like the United States, where it's more widely accepted.
In some European countries, taking leftovers may not be considered rude but simply uncommon or unusual. However, in other places, it might be seen as unusual or unnecessary, as European portion sizes in restaurants tend to be smaller compared to some other regions.
If you are unsure about the local customs, it's a good idea to observe what others around you are doing or to ask the restaurant staff discreetly if taking leftovers is acceptable. Some upscale or fine-dining establishments might not encourage taking leftovers, while more casual or family-style restaurants may not have any issues with it.
If you really want to take leftovers, you can politely ask the server or staff if it's possible to pack the remaining food to take away. Being considerate and respectful of the local customs will generally be appreciated in any situation.
Overall, while it may not necessarily be considered rude, taking leftovers from a restaurant in Europe might be less common or even perceived as unusual in some places. Always being aware of the cultural norms and using polite communication will help you navigate these situations with respect and sensitivity.