When you buy a drug, you scratch the panel, you send a text message with the number that you see, and you get a response instantly at the counter if the drug is genuine or fake."

VOA: standard.2010.06.07

So if you were wanting a pretty precise number on how many calories are in a food, you'd send it to a lab.

所以如果想要一个精确的,食物所含卡路里的数值,就把食物送到实验室

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选