At the restaurant, order more than you can eat!
When you go to the restaurant in China either you will invite, either you will be invited.
The person who invites will order the food. Thus he will know what he has to pay. He should order enough food so that there is always food on the table.
It is very unpolite when your guest doesn't have enough to eat, when there is no more dishes on the table.
That is why you always have more to eat than what you can eat:
When you are two person eating at the restaurant, you should order at least 3 dishes.
When you are three, you should order at least 4 or 5 dishes.
When you are four, you should order 5 or 6 dishes.
Of course if the dishes are almost empty the guest will simply pretend he is full. No one will finish the dishes at least on formal occasions.
Also the inviter if he sees that the dishes are almost empty will order more dishes and pushes his guest to eat, serve him, tell him to eat... But of course the guest should refuse loudly and say that he is full. Then the inviter will insist even more and order more dishes!
Anyway this customs means that there is always a lot of waste, many dishes are not finished at the end of the meal.
Now you can ask for a doggy bag and take the food back home. However I believe that on official occasion it can look too stingy and make you lose face! Thus it is better to leave the food.
Also when taking the food back home you will use many plastic boxes...
The left over won't be lost for everyone: they will be given to feed pigs.
Where does this custom comes from?
China has known many famine throughout its history. Why then do Chinese people waste so much?
In fact at home they don't waste. On the contrary Chinese families will keep the food longer than we do in France and still eat it.
But in the restaurant there should be abundance! This is certainly due to famines. Your guest should have plenty to eat!