I will start with a little example:
When I was younger, I used to live in a culture where green tea was cherished. We used to get green tea servings in very small cups. A cup of tea looked like the one above. It was pretty satisfactory a size for a serving.
In 2000 I moved to US. A few years down the line I was at a QT gas station and had my first iced "green apple green tea". They had that offered in 44 Oz cups (1.3 Liters), and I had that fairly often. That messed up my perception of green tea servings forever. Now I can't feel satisfied with a little cup of green tea, and I get my green tea served in at least 250ml cups now.
Similar is the case with coffee. My friends here in Spain have coffee in little cups, whereas my system requires coffee to be served in 250ml or so. I do not know if I am pleasing the taste buds or I am filling up a more primitive desire of filling my stomach with it.
There is a primitive psychological connection that governs the desire to eat with the pleasant taste. Maybe the connection gets reinforced by habits, and once reinforced it's really difficult to go back to enjoying small servings just for the sake of taste. In words of an ex addict "when you have tasted excess, everything else tastes bland".
And that might be one of the biggest reason for obesity in America. The perception of taste is so strongly linked with the desire to fill stomach that it's very difficult to feel satisfied with a small serving size. Is it possible to break that connection just by changing habits alone, or would any drug maker have to make a blocker for that connection? if someone does, that could become the medicine that saves America.
