What I have: injection-site erythema · 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 is the most likely explanation, and how would I confirm it?
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 injection-site erythema 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 injection-site erythema on the same daily row for a fortnight and the two patterns separate without any further cleverness. Nothing here is medical advice.
If it persists at an adequate intake, it needs blood work rather than more speculation.
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.
In practice, 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.
Energy deficits above roughly a thousand kilocalories a day are associated with measurable reductions in resting metabolic rate, spontaneous activity and subjective energy in controlled studies.
Weigh three days of intake honestly. That answers this most of the time.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe 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.
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.
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.
Start with the actual intake, because a substantially suppressed appetite produces deficits far larger than intended and fatigue is the first symptom.
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.
On the detail: fatigue that appeared abruptly, rather than gradually with the deficit, is a different pattern and points away from intake.
Ferritin as an acute-phase reactant is a recognised limitation and is why it is interpreted alongside an inflammatory marker.
If it persists at an adequate intake, get bloods rather than more theories.
edited 23 May 2026 by deamidation_watch — corrected a unit error in the worked example
The relevant physiology is that a large deficit reduces both available substrate and spontaneous activity, and the second is often mistaken for the first.
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.
Abrupt onset points away from the deficit and towards something else.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.