Lydia Thurstan's testosterone therapy claims, fact-checked

What did @lydiathurstan1 actually say?

The creator argues that testosterone replacement therapy is increasingly used in female bodybuilding because hard dieting, contraceptive pill use, and chronic stress can suppress normal hormonal function. Her core message is that TRT in women is about restoring what was lost, not adding more, and that blood work is non-negotiable before anyone considers it. She also flags that being an athlete alone does not make you a candidate, since levels may be completely normal.

She closes with a disclaimer that this is not medical advice and encourages viewers to research independently. The framing is broadly responsible for a TikTok video. But there are some specifics worth pulling apart.

Does the science back this up?

Partially, yes. The evidence for testosterone therapy in women is real but narrower than the video implies. The strongest clinical evidence covers hypoactive sexual desire disorder (HSDD), not general recovery or body composition optimization.

A 2019 systematic review by Davis et al. in The Lancet Diabetes and Endocrinology, covering 36 randomized controlled trials, found that testosterone improved sexual function in postmenopausal women. The evidence for lean mass benefits existed but was modest, and evidence in premenopausal athletes is considerably thinner.

The claim that dieting and oral contraceptives suppress testosterone is well-supported. Caloric restriction can lower luteinizing hormone and androgen output. Combined oral contraceptives raise sex hormone-binding globulin, which binds free testosterone and can reduce bioavailable levels significantly. A 2005 study by Panzer et al. in the Journal of Sexual Medicine found that women using oral contraceptives had significantly lower free testosterone and higher SHBG even after stopping the pill.

Where the science gets murkier is in the leap from suppressed labs to symptomatic deficiency to clinical TRT in healthy athletic women. There is no agreed reference range for female testosterone that is universally validated across labs and assays, which complicates diagnosis considerably.

What did they get wrong (or right)?

She gets the principle right. Saying the goal is to "replace what was missing" rather than add more is the correct clinical framing for TRT in any patient. That distinction matters, especially in a space where PED misuse is common. Credit where it is due.

She also correctly states that blood work is mandatory and that athletic status alone does not qualify someone. That is accurate and responsible messaging.

What she gets wrong, or at least incomplete, is the implied breadth of benefits. Listing improved "recovery, lean muscle mass, overall body composition, libido and energy levels" as expected outcomes conflates findings from different populations and different study designs. The lean mass and recovery data in women is largely drawn from postmenopausal or clinically deficient populations, not healthy premenopausal athletes with mildly suppressed labs. Applying those endpoints to a bodybuilding audience is a meaningful extrapolation.

She also references PEDs at the end, which is a different category entirely from TRT. Lumping them together in the same sentence, even briefly, is worth noting.

What should you actually know?

If you are a woman considering testosterone therapy, the first conversation is not with a coach or a TikTok video. It is with a clinician who can run a full hormonal panel, including total testosterone, free testosterone, SHBG, LH, FSH, and estradiol, and interpret them in the context of your symptoms and menstrual cycle phase.

Testosterone assay accuracy in women is a known problem. Standard immunoassays are not validated at the low concentrations typical of female physiology. Mass spectrometry-based testing is more reliable but less widely available. This means your lab result can vary substantially depending on where it was run.

The Endocrine Society does not currently have an approved indication for testosterone therapy in premenopausal women outside of specific clinical contexts. The Global Consensus Position Statement on the Use of Testosterone Therapy for Women, published in 2019, recommends against use for general well-being or to enhance athletic performance. That does not mean it is never appropriate. It means the bar is higher than a suppressed lab value alone.

If you are taking an oral contraceptive and experiencing low libido or fatigue, the first clinical question is often whether the OCP itself is the problem, not whether you need additional hormones on top of it.