Details up front: vomiting · 1,000 kcal.
I have a result I cannot explain, and I would rather diagnose it than guess.
I have checked the obvious explanations and eliminated the two easiest ones.
What would you check first, and what would you conclude from each outcome?
Start with what 1,000 kcal a day leaves you room for, because at that intake the deficit is a live competing explanation rather than a footnote. Protein is 4 kcal per gram, so 100 g costs 400 kcal — 40 per cent of the entire day's energy — and everything else has to come out of the remaining 600. A day that misses protein at 1,000 kcal has missed it by a wide margin, and vomiting that tracks those days is a nutrition signal. Then separate the two by timing: a dose effect is periodic and phase-locked to the injection or to an increase, and a deficit effect is monotonic and gets worse the longer the intake stays at 1,000. Log intake, protein and vomiting on the same daily row for a fortnight and the two patterns separate without any further cleverness. Nothing here is medical advice.
The honest answer is that this is usually fixable by eating more, which is unwelcome advice in this context.
Carbohydrate intake specifically affects training performance and perceived energy at a given total intake, which is why very low carbohydrate approaches feel worse in the gym at matched energy.
More usefully, dehydration from reduced fluid intake alongside reduced food intake produces headache, lethargy and postural dizziness, and is the cheapest thing on the list to correct.
Ferritin as an acute-phase reactant is a recognised limitation and is why it is interpreted alongside an inflammatory marker.
Attributing a symptom with a wide differential to the most recent change is a common and expensive error.
Weigh three days of intake honestly. That answers this most of the time.
edited 4 Jul 2024 by amara_nwachukwu — removed a claim I could not source
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Browse resultsStart with the actual intake, because a substantially suppressed appetite produces deficits far larger than intended and fatigue is the first symptom.
Iron deficiency is common, particularly in menstruating women, and low intake plus a reduced red-meat share makes it more likely. Ferritin is the test, and it is an acute-phase reactant so it needs interpreting alongside CRP.
Fatigue that appeared abruptly, rather than gradually with the deficit, is a different pattern and points away from intake.
Research-use compounds are not approved for human use.
Check fluid and sodium before anything more exotic.
The short version: check intake, check hydration, check iron and thyroid if it persists, and only then attribute it to the compound.
Hypothyroidism, sleep apnoea, depression and anaemia all present as fatigue and all become more likely rather than less in this population, so attribution to the compound should be a diagnosis of exclusion.
In practice, three days of honest weighed intake usually settles this. Estimated intake in this situation is systematically wrong and usually wrong in the direction that hides the problem.
If it persists at an adequate intake, get bloods rather than more theories.
To be exact about it, this is the complaint with the widest differential and the one most often attributed too quickly.
A deficit beyond about a thousand kilocalories a day reliably produces fatigue, reduced training performance and reduced spontaneous movement. With appetite suppressed, deficits of that size arrive by accident rather than by plan.
Self-reported intake underestimates measured intake by twenty per cent or more in doubly labelled water comparisons.
Abrupt onset points away from the deficit and towards something else.
The relevant physiology is that a large deficit reduces both available substrate and spontaneous activity, and the second is often mistaken for the first.
Sleep quality often changes during rapid weight loss in both directions, and sleep debt produces fatigue that no amount of dietary adjustment will fix.
The caveat is that fatigue with breathlessness, chest symptoms or sudden onset needs assessment rather than dietary adjustment.
Sleep is a variable here too, and no amount of eating fixes sleep debt.
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