I know salt has very very few calories. Few enough that everyone says it has zero.
But does it really truly have zero calories? Like if I ate five pounds of salt, would that still be zero calories?
I know diet sodas really have calories in them. And pretty much everything else that advertises as zero calories.
And I know eating too much salt makes you retain water and gain weight.
… but does it have calories?
No, it has no calories.
It may help to look at it this way: “Salt” is actually sodium chloride (NaCl). So, the only possible way it could have calories is if the body could store or burn either or both the Na and the Cl. But that doesn’t, and can’t, happen. Basically, from a human physiology point of view, if something has no carbon in itself, it has no calories.
Another way is to recall that calories are a measure of heat energy. So, if something can’t be burned (in a “fire”), it can’t add heat (to that “fire”), and hence it can’t have calories. Na and Cl can’t be burned.
(Now I wait for someone to pop in with some obscure reaction demonstrating that it’s possible for NaCl to contribute to calories . . .)
Of course too much salt- like 5# is dangerous. :eek:
About 8% of Americans have to closely regulate their Sodium intake. For a unknown but likely around the same %, lower sodium is a good idea. Regular amounts of sodium seems to have no appreciable effect in the rest of the population.
What I am saying is: before going on a “low sodium diet” consult your MD.
NaCl has no calories. Of course you might retain extra water weight if you ate a lot of it.
thanks for the answers- that makes more sense already.
but my salt says it has salt (NaCl, I guess), potassium silicate, dextrose, and potassium iodide.
So can any of that be absorbed? What about stuff like… that red sea salt you get at gourmet stores that has minerals or something in it? Is it only calorie-free if it’s absolutely pure?
… and water- okay, I know H2O has no calories, but what about all the impurities? Like minerals and fluoride and stuff?
Potassium silicate, dextrose, and potassium iodide. All trace amounts- by the time you get some food value out of the dextrose you’ll be puking your guts up or in the ER from too much salt.
The other minerals in the other salts have no calories either, same with the minerals in water. Basicly- minerals have no calories. You are not a Horta. 
[mode=polite concern]Would I be right in thinking you haven’t got the anorexia licked yet?[/mode]
Not to mention the OCD.
still working on it. although this was seriously mostly just honest curiosity, not pure obsessive insanity.
and thank you, Dr. Deth.
Your body can only assimilate the energy from organic compounds. That is, those made out of some combination of carbon, hydrogen, and oxygen. Your body isn’t a furnace; you can’t just throw anything in it and expect it to burn. Your enyzmes only work on a select number of compounds. Namely, proteins, fats, and sugars.
If we could obtain energy from NaCl, we’d be rock-eaters. There would be no need to grow vegetables because we’d be able to eat the dirt they grow out of. Which would be quite nifty (niftier even than being able to photosynthesize). There are some organisms (bacteria) that can assimilate the energy from inorganic compounds. They are called lithotrophs. Most feed on sulfides, if I’m not mistaken. Even lithotrophs are selective on the stuff they eat.
Well, Na in the elemental form can certainly start a fire…
Well, I was a little worried… given that anyone’s salt intake per day is going to be measured in grams, and any impurities in it (with putative food value) in milligrams, your concerns over it sounded like those of someone who’s determined to eliminate all-l-l-l-l-l possible calories from her diet.
If we’re talking about ‘salt’ as in the chemical Sodium Chloride, then as others have said, the food value is absolutely nil. If, on the other hand, we’re talking about the culinary commodity called ‘salt’ - which may be a mixture of several things - then there may be traces of food value in the mix; for example in a very unrefined sea salt, there might be remnants of algae, plankton, etc - but I would guess we’re talking about traces so small that they’re probably negated by the effort of raising the spoon to your mouth - not to mention the obvious poisoning outcome resulting from eating too much salt.