How do I tell constipation from an energy deficit on 1,100 kcal a day?

Setup, so nobody has to ask: constipation · 1,100 kcal.

This is not behaving the way I expected and I want to understand the discrepancy before I act on it.

I have photographed the current state and recorded the conditions, so I can answer follow-up questions precisely.

Is this recoverable, and how would I tell?

If it persists at an adequate intake, it needs blood work rather than more speculation.

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.

The relevant detail is that sleep quality often changes during rapid weight loss in both directions, and sleep debt produces fatigue that no amount of dietary adjustment will fix.

Sleep restriction produces measurable decrements in subjective energy and in training performance independently of energy intake.

Abrupt onset points away from the deficit and towards something else.

Start with the actual intake, because a substantially suppressed appetite produces deficits far larger than intended and fatigue is the first symptom.

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.

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.

Self-reported intake underestimates measured intake by twenty per cent or more in doubly labelled water comparisons.

Nothing here is medical advice.

If it persists at an adequate intake, get bloods rather than more theories.

The honest answer is that this is usually fixable by eating more, which is unwelcome advice in this context.

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.

Research-use compounds are not approved for human use.

Sleep is a variable here too, and no amount of eating fixes sleep debt.

The relevant detail is that this is the complaint with the widest differential and the one most often attributed too quickly.

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.

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.