@riana_koala's estrogen surprise claims, fact-checked

What did @riana_koala actually say?

In a 608K-view TikTok, @riana_koala listed three changes she attributed to estrogen therapy as a trans woman: a shift in sexual orientation or attraction, longer eyelashes, and a two-shoe-size reduction in foot size. She presented all three as unexpected and personal. The sexuality claim was delivered as a joke, but the underlying assertion, that HRT changed who or what she's attracted to, is a real phenomenon worth taking seriously. Same with the foot claim, which is the most physiologically contested of the three.

She did not specify her hormone regimen, dosage, duration of therapy, or whether she takes anti-androgens alongside estrogen. That context matters for evaluating what's driving any of these changes.

Does the science back this up?

Partially, depending on the claim. The eyelash claim has the strongest mechanistic support. The sexuality claim is real but complicated. The foot-size claim is the most overstated.

On eyelashes: estrogen is known to influence hair follicle cycling. Androgens, particularly DHT, can miniaturize follicles in scalp hair, but eyelashes behave differently. Estrogen and progesterone appear to prolong the anagen (growth) phase of eyelash follicles. A 2018 review by Blume-Peytavi et al. in the Journal of the European Academy of Dermatology and Venereology noted sex hormone receptors in hair follicles and their role in follicle-specific growth cycles. This is real biology.

On sexuality: research does suggest HRT in trans women can shift subjective experience of attraction. A 2020 study by van der Miesen et al. in Archives of Sexual Behavior found that a meaningful proportion of trans women reported changes in sexual attraction after starting HRT. But whether this is hormonal, psychological, or social is not settled.

On foot size: this is where the claim gets shakier. Feet don't shrink. Ligaments can relax slightly with lower androgen levels, and reduced muscle mass may change how a shoe fits, but bone structure doesn't remodel by two full sizes in adults.

What did they get wrong (or right)?

She got the eyelash claim right. That one is biologically plausible and consistent with what endocrinology literature says about estrogen's effects on hair follicles. Credit where it's due.

The sexuality claim is real but was framed as comedy, which undersells how significant and sometimes disorienting this experience is for people on HRT. The van der Miesen data suggests this isn't rare. It deserves more than a punchline, though the humor likely made it accessible to a wide audience.

The foot claim is the most problematic. Two full shoe sizes is a dramatic number. Adult foot bones do not remodel under estrogen. What likely happened: reduced foot swelling, softer tissue, or a change in arch height from ligament laxity, all of which can affect shoe fit. But framing this as feet physically shrinking is inaccurate and potentially misleading for people trying to set realistic expectations before starting HRT. A 2011 study by Bhave et al. in Foot and Ankle International documented hormonal effects on foot ligament laxity, but nothing approaching two full shoe sizes from hormonal transition alone.

What should you actually know?

If you are considering or currently on feminizing HRT, here is what the evidence actually supports. Estrogen does cause real, documented physical changes: breast development, redistribution of body fat, reduced body and facial hair, and changes in skin texture and thickness. Some of these changes take years. None of them are guaranteed to match any specific person's experience, including @riana_koala's.

Changes in sexual attraction during HRT are documented but not universal, and the mechanisms are not fully understood. If you experience this, it is not unusual, but it also does not happen to everyone.

Eyelash changes are plausible and some trans women do report them. But individual variation in hair follicle sensitivity to hormones is significant. Do not expect identical results.

Foot size changes of two full sizes from HRT alone are not supported by skeletal biology in adults. If your shoes fit differently after starting estrogen, that is likely a soft tissue or swelling change, not bone remodeling. Set realistic expectations before starting therapy, and have those conversations with a qualified provider, not a TikTok comment section.

Bottom line

@riana_koala's video is entertaining and largely well-intentioned. One of her three claims is well-supported, one is real but needs more nuance, and one is exaggerated in a way that could set unrealistic expectations. For a platform with 608K views, that ratio matters.