What calories physically are, and how things like water and celery have none whatsoever?

Question

What calories physically are, and how things like water and celery have none whatsoever?

In: Biology

Answer 1

Its the unit of energy like what everyone said.

thye USED to actually put the food in a container with water, BURN the food, then measure the water temp raise. Celery have calories, its just that it takes more energy to chew them then what you gain, hence a negative en intake. Which is kinda misleading to call it 0 cal food.