Posting this because the summary going around does not say what the paper says, and the difference matters for how people here are using it.
Mostly the deficit, and the useful part of that answer is that it is testable. Fatigue driven by a deficit tracks intake, improves within a day or two of eating properly, and worsens on the days you eat least. Fatigue that is flat regardless of intake, or that arrives on a fixed day after dosing, is behaving like a drug effect. Before assuming either, rule out the boring causes — iron, B12, thyroid, and sleep — because a fast deficit unmasks deficiencies that were previously subclinical.
Where I think it is weakest: the completion rate deserves as much attention as the headline, because a large effect among those who finished is a different claim from a large effect among those enrolled.
What I actually want to know is whether the fatigue is a direct drug effect or simply the caloric deficit, because the answer changes what you do about it. I would rather have one careful answer than five confident ones.
tommy_boulder said:Mostly the deficit, and the useful part of that answer is that it is testable.
That holds where the measurement is reliable. Where it is noisy — and a lot of what gets tracked here is noisy — the same reasoning produces confident nonsense.
tommy_boulder said:Mostly the deficit, and the useful part of that answer is that it is testable.
This is where I part company with the consensus forming above. Pushing back on the consensus forming here. Consistency is not the same as correctness, and a board that agrees with itself quickly is usually agreeing with the first person who sounded certain.
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Browse GL BiochemTaking the question as asked, rather than the general version of it. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.