Why is it correct to say "fewer calories" when calories are continuous? [duplicate]

This question, "Discrete Units of a Continuous Quantity", asks whether units of a continuous quantity should be spoken of as discrete or continuous.

The top answer states

The rule is simple, and you obviously know it: discrete quantities require the use of "fewer" and continuous quantities require the use of "less".

Calorie, as a unit, requires the use of "fewer". Energy, as a continuum, requires the use of "less".

"Fewer calories means less energy."

I do not understand the logic here though. Calorie is a unit, yes, but it is a continuous unit (it is possible to have half a calorie, or 4.582394 calories). Since a calorie is such a small unit of energy compared to what it is usually used for (food energy and human metabolism), it is very seldom expressed in a fractional form and instead is rounded (usually to the nearest 10 or higher).

Why then should "fewer" be used with calorie instead of "less"? Is there another relevant rule than just "continuous quantities use "less" and discrete quantities use "fewer"?

Solution 1:

Divisibility does not mean something is not countable or that it isn't a discrete unit, requiring use of 'fewer'. A calorie is not 'energy' it is a 'unit of energy', and therefore, countable and discrete, even though it's divisible. It's divisible into further discrete units - half a calorie, in this case, is still a discrete unit.

Using another example, you would have 'fewer' jars of peanut butter, even though someone might have eaten half of the peanut butter in some of the jars. You could even cut the entire jar in half, none of that matters, you still have fewer jars. And you also have less peanut butter, in the same way that fewer calories means less energy. The calorie corresponds to the jar, not to the peanut butter (that would correspond to the energy the calorie measures).

It doesn't matter that there is 'less' peanut butter in some jars than in others any more than it would matter if some of the jars were a gallon in size, and some were just single-use jars with two tablespoons of peanut butter inside. Put another way, your 'half a calorie' is still a unit, and thus, you'd still say 'fewer calories'.

Solution 2:

it is possible to have half a calorie, or 4.582394 calories

It's also possible to have half a cow or 4.582394 cows. Indeed, the same is true for almost every countable noun that existed at the time when "fewer" came to be the word we used with countable nouns. Perhaps it's impossible to have half a thunderclap...

This shows that it's a mistake to think that the existence of fractional quantities means that a noun is uncountable. Rather, countable nouns are those that can be modified by a number and which have singular and plural forms.

Solution 3:

While calories are continuous to scientists, most lay people don't think of them that way. Food and activity calories are always reported in whole numbers, often only precise to hundreds or thousands, because for most people's purposes any more accuracy is not meaningful or useful.

So in common use we treat them as discrete units, and the language we use reflects that. We use "more" and "fewer" when comparing things, and ask things like "How many calories does an egg have?" and "How many calories do does an hour of exercise use?" (rather than "How much", which would be used for non-countable quantities).

Solution 4:

You shouldn't use "fewer" instead of "less" necessarily. Look at this NGram:

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In many cases "less calories" is more common than "fewer calories". In no case is there an enormous difference either way.

It depends on how conceptually you see what it is you're describing with either "less" or "fewer". In this case it's whether you see the calories as individual units (plural), or one sum of things, ie., energy (singular). Oxford Online Dictionary blog explains:

(In a supermarket/store) Ten items or less.(Correct or incorrect?)

Firstly, having absorbed the guidelines above, you may suppose that some supermarkets are grammatically on the ball by displaying notices at checkouts that state ’10 items or fewer’ (fewer rather than less being the right choice because it’s referring to items, that is, a number of things?). In fact, there were reports a few years back that Tesco had replaced their signs reading ’10 items or less’ with ones which said ‘Up to 10 items’, so as to placate the sticklers. Sorry, no need! This is an example of hypercorrection. Pocket Fowler’s Modern English Usage puts it very succinctly:

‘Supermarket checkouts are correct when the signs they display read 5 items or less (which refers to a total amount), and are misguidedly pedantic when they read 5 items or fewer (which emphasizes individuality, surely not the intention).’
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The point is fewer is used for plural and less for singular. But the mental notion of whether something is singular or plural seems to be an influencing factor in whether "less" or "fewer" is used.

Look at the difference in usage between: