The traditional definition of empty calories would be something like a spoonful of sugar.
That's an extreme example, but the idea is that the food in question provides calories without nutrients. So there is such a thing and it makes plenty of sense.
No, a spoonful of refined white sugar contains 100% calories.
It does not contain any minerals, vitamins, protein, essential fatty acids, micronutrients or antioxidants, which in the context of this discussion, is what is meant by saying it has no nutrients.
There are only 4 macronutrients (foods metabolism can run on): carbs, fat, protein, & ethanol. So if you believe protein & fat are nutrients, then you must believe carbs are as well.
'Macronutrients' are not diet 'nutrients'. Nutrients are chemicals the body needs an external supply of. Building blocks for cells and structures. They have nothing to do with metabolism.
I don't need carbs to be alive, be healthy and be energetic. The nutrition they give me is pretty much nill relative to other food groups such as fat and protein.
I think the poster is referring to them as empty calories in the sense that they provide no nutritional value. They get processed into blood sugar very quickly but do not provide the body anything essential.
Then why am I more energetic now after starving my body of carbs, than I was before the diet when my diet existed entirely of carbs? Energy does not need to be taken from carbs to survive or be healthy.
That's an extreme example, but the idea is that the food in question provides calories without nutrients. So there is such a thing and it makes plenty of sense.
(USDA takes my side: http://www.choosemyplate.gov/weight-management-calories/calo...)