Setup, so nobody has to ask: hair thinning · 1,100 kcal.
I noticed this today and I have not touched anything since, in case the state is diagnostic.
I have not discarded anything yet, so a test is still possible if that is the recommendation.
Should I be treating this as a failure or as noise?
Start with what 1,100 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 — 36 per cent of the entire day's energy — and everything else has to come out of the remaining 700. A day that misses protein at 1,100 kcal has missed it by a wide margin, and hair thinning 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 1,100. Log intake, protein and hair thinning on the same daily row for a fortnight and the two patterns separate without any further cleverness. Nothing here is medical advice.
Start with the actual intake, because a substantially suppressed appetite produces deficits far larger than intended and fatigue is the first symptom.
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.
| Event | Active arm | Placebo arm | Timing |
|---|---|---|---|
| Nausea | 40–45 % | 15–20 % | Peaks 1–2 wk after each step |
| Vomiting | 15–25 % | 5–8 % | Follows nausea |
| Diarrhoea | 20–30 % | 10–15 % | Early, variable |
| Constipation | 20–25 % | 8–12 % | Later onset, persistent |
| Discontinuation for GI events | 4–7 % | 1–2 % | Mostly during escalation |
Ranges span agents and doses; read the specific prescribing information for a specific figure.
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.
Self-reported intake underestimates measured intake by twenty per cent or more in doubly labelled water comparisons.
Check fluid and sodium before anything more exotic.
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Browse resultsAnswering this needs to know the size of the deficit, since fatigue tracks it closely and predictably.
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.
On the detail: 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.
Ferritin as an acute-phase reactant is a recognised limitation and is why it is interpreted alongside an inflammatory marker.
Nothing here is medical advice.
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.
Put another way, 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.
If it persists at an adequate intake, get bloods rather than more theories.
Dehydration and low sodium intake produce fatigue that is indistinguishable subjectively and much easier to fix.
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.
Sleep restriction produces measurable decrements in subjective energy and in training performance independently of energy intake.
Sleep is a variable here too, and no amount of eating fixes sleep debt.
edited 20 Feb 2025 by cal_hennessy — added the placebo-arm figures
This is the complaint with the widest differential and the one most often attributed too quickly.
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.
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.
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