In Chinese culture, wasting food is generally considered to be a discourteous behavior regardless of whether you are a foreigner or a local. Food holds a special significance in Chinese culture, and there is a strong emphasis on valuing food as it represents the effort and hard work that goes into producing it. Additionally, Chinese society places great importance on hospitality and showing respect to hosts, which often includes finishing the food that has been offered.
When it comes to buffets, wasting food can be seen as particularly disrespectful, as it may imply that the person is taking more than they can eat or not appreciating the abundance of food provided. This attitude is not limited to Chinese people but is generally shared by many cultures that value food and respect for resources.
However, it is also essential to acknowledge that cultural norms can vary, and there might be individual differences in how people react to such situations. In modern times, with increasing globalization and exposure to diverse cultures, some Chinese individuals might understand that different cultures have different dining norms and might be more forgiving if foreigners do not finish their food.
If you find yourself in a situation where you cannot finish your food at a Chinese buffet, it is always a good idea to show your respect by not wasting large amounts of food deliberately. You can take a small portion first and go back for more if you still feel hungry. Also, it's helpful to communicate your cultural differences politely if necessary, and most people will understand and appreciate your efforts to be respectful and considerate.