The idea that hormones only flip DNA switches holds up, but the claim that HRT just changes how much hormone is in your blood runs into direct counter-evidence.

The DNA-switch framing has real support: other research shows a hormone turning on a specific gene through a DNA switch, and estrogen flipping switches via its receptor rather than directly changing the body — though each of those studies looked at a single hormone and a single gene, so the picture is narrower than a general rule. The stronger claim that a regimen can only change how much hormone is in your blood is where things get shaky. Other research on growth hormone treatment found it improved blood sugar, insulin resistance, weight, blood pressure, and liver enzymes without necessarily changing hormone levels, which is hard to square with the idea that the only lever is quantity. The middle claim — that shifting blood hormone levels matters when testosterone suppression is inadequate or estrogen is low — is well supported, with studies in men with low testosterone, in prostate cancer treatment, and on estrogen and sexual function all showing that changing circulating hormones makes a measurable difference. As for the idea that optimal levels mean the regimen does nothing beyond your baseline, we couldn't find studies in our databases addressing that directly.