I have watched with interest, amusement and sometimes with amazement how much food people take with them on the buffet line and don't eat. I have observed people walking away from huge amounts of food. Yes, sometimes I don't eat some things that I don't like- but I have seen enough food removed from an individual that could feed two adults.
I usually sample a small amount of food when I go through a buffet. In that way I
a. sample a variety of foods to determine what I will want more of
b. am able to eat most of the food on my plate before it becomes cold
c. am able to leave the table leaving an empty plate behind.
Returning to the buffet for more food is not a hardship.
While I won't get into a philosophical discussion about people starving in various parts of the world, I would like to bring up one practical matter. The more food that is wasted is merely reflected in increased fares for future cruises.