Zero-calorie drinks, are they really 0 kcal?

According to the Food and Drug Safety Administration's standards for food labeling, if the calorie content is less than 5 kcal per 100 ml, it can be marked as 0.

100ml 5kcal!

Because it contains a very small amount of calories, strictly speaking, it is not 0 kcal.

Since the energy expended during digestion is greater than the calories of the food consumed, it is permitted to label it as 0 kcal.