In the following passage, should "consistent" or "constant" be used?
We all know that eating later in the day isn’t good for our waistlines, but why? A new study weighed in on that question by comparing people who ate the same foods – but at different times in the day.
“Does the time that we eat matter when everything else is kept consistent/constant?” said first author Nina Vujović, a researcher in the division of sleep and circadian disorders at Boston’s Brigham and Women’s Hospital.
Both are acceptable, but "constant" is probably better.
"Constant" is the opposite of "changing", and refers to absolute values, rather than relative ones, so it fits the context.
"Consistent" means it stays the same relatively, meaning with respect to something. It does not mean it doesn't change at all. In that passage, "everything else" needs something understood that it keeps consistent with. But what? There's nothing left to compare "everything else" with, unless it means "with respect to how everything else was before", which is the definition of "constant".
An argument for choosing "consistent" might be that "constant" has a feeling of absolute rigidity and precision. A scientist or mathematician would use the word to be clear, but a lifestyle journalist, for instance, might choose "consistent" because it's a nicer, softer word.
