Most of us Sri Lankans spend a fair amount of time as parents, elders or teachers teaching good manners to our young ones. Most of these so called good manners (or just manners as most of us say) are willingly adopted practices by us from our colonial masters.
One such good manner that we have been taught repeatedly when we were kids was to show our host (when we visit a relative or friend) that we are satisfied with the quantity of food that has been served.
This is shown by leaving a small quantity of drinks in your glass / cup or leaving some food in your plate (mostly the former). Some people do this to show their societal highness as well. We used to refer this practice (with a touch of humor) as "leaving manners at the bottom of the glass".
Apparently a nice behaviour and a way of showing your decency, this practice leads to unnecessary waste of food and also the promotion of food wasting psyche. Unless you cannot totally consume what you have been offered, why should you leave some food on your glass or plate?
Hosts should also get used to serve food in base containers so that visitors can take whatever quantity they want into their own containers, without spoiling a large amount of food..
When ever you take a sip of juice or bite of sandwich don't forget that....
..... as the United Nations Food and Agriculture Organization estimates that nearly 870 million people of the 7.1 billion people in the world, or one in eight, were suffering from chronic undernourishment in 2010-2012.