Does testosterone recover on weight loss alone in men?

I have three data points across nine months, which I hope is enough to see a trend.

I would like to know whether this claim survives contact with evidence.

If the answer is "nobody has tested that", I would like that stated so I can stop looking.

Is this actually true, and what is the evidence?

Put another way, this is answerable in general terms and not in individual terms, and the difference matters more in endocrinology than almost anywhere else.

Leptin tracks fat mass closely and falls with weight loss, which is one of the mechanisms behind the counter-regulatory drive that makes maintenance harder than loss.

Relative to absolute, worked

The last two rows describe the same finding. Only one of them is used in headlines.

Cortisol has a pronounced diurnal rhythm with the peak shortly after waking; a random afternoon sample is close to uninterpretable without knowing the draw time.

Record the draw time with the result, or the result is worth much less than you paid for it.

Answering this needs the reference interval the laboratory used, because reference intervals for these analytes differ between methods enough to change a result from normal to abnormal.

Testosterone in males is both diurnal and pulsatile, and the conventional advice is an early-morning fasting sample repeated on a second occasion before anything is concluded.

It helps to be literal here: growth-hormone secretion is pulsatile enough that IGF-1 is used as the integrated proxy, and IGF-1 itself is affected by nutritional status.

Free and total measures can diverge through the binding protein. Read both.

edited 11 May 2024 by tess_amankwah — added a caveat about sampling

Answer first: the class has documented effects on the gut hormone axis by design, and the claims that travel furthest are usually about axes it does not directly touch.

Ghrelin, peptide YY and glucagon-like peptide-1 itself all shift with sustained energy restriction, and those shifts partly oppose continued weight loss. That counter-regulation is a well-described phenomenon and is not specific to any drug.

To be exact about it, thyroid-stimulating hormone has a diurnal variation of a few tenths and a wide reference interval, so small movements within the interval are not findings.

The counter-regulatory hormonal response to weight loss is well documented in the physiological literature and persists for a long time after the loss itself.

Weight change moves several of these axes on its own, so attribution needs care.

Start with what is being measured and when. Most hormone assays are exquisitely sensitive to sampling time, fasting state and recent sleep, and those three explain a great many surprising results.

Assay methods differ: immunoassay and mass-spectrometry results for the same steroid can differ enough to matter, particularly at low concentrations.

The caveat is that endocrine results need a clinician who can see the whole panel and the person attached to it. This is background only.

Compare against the reporting laboratory's own interval, not a remembered one.

The honest answer is that the direct effects are well described, the indirect ones follow weight rather than the drug, and the distinction is often collapsed.

Sex-hormone-binding globulin rises as insulin resistance falls, which lowers free hormone fractions without any change in production. A free measure and a total measure can therefore move in opposite directions.

Diurnal variation for cortisol, testosterone and thyroid-stimulating hormone is characterised well enough that sampling time is part of the result rather than a detail about it.

One abnormal value on a wide panel is usually statistics. Two on a repeat is a finding.

edited 11 Jul 2024 by triple_agonist_q — added the placebo-arm figures