A few questions for you to think of then -- or rather a few things I think you should consider with your statements:
1. How does ACA affect the corpus of knowledge and medical practice gathered prior to the ACA being in effect? How does it affect late 19th, and early and mid 20th century medical knowledge and practice, which occurred prior to health insurance of any kind, nevermind ACA-compliant, being widespread? This corpus of knowledge and practice continues to propagate even now. I've read a handful of recently published medical textbooks and there are definitely parts that are pretty much the same as the textbooks of the early 20th century, just with slightly updated language.
2. What are the possible confounding factors in the use of health insurance by men vs women? For example, could men just be more hesitant to see a doctor, and thus less likely to make use of health insurance? Does the average life expectancy of women result in more use of health insurance later in life than for men? Are medical procedures that are specific to women that add to the cost of their care, such as mammograms, pap smears, etc? Seeings as how in the US health insurance is a practical requirement to getting medical care, and lack of it is punished financially in various ways from taxes to just having medical care be more expensive when you truly need it, means most people will try to have _some_ kind of health insurance, even if they don't think they need it for actual health reasons. So despite a perception of not needing health insurance, men are incentivized to have health insurance they don't use?
3. Does the ACA guarantee in any way that medical professionals no longer hold any bias due their previous training, especially if such training occurred prior to the introduction of the ACA? Does the ACA similarly guarantee that women and men are not only able, but choose to pursue medical care and participate in medical studies at percentages matching the general population?
Your point about men subsidizing women with regard to health insurance premiums may be perfectly valid, I am not disputing you on that point. I am disputing that it is salient to the tradition and practice of medicine in the western world in the modern era, until very recently historically, and that these traditions and biases will affect data sets gathered from people who are directly affected by these biases and traditions to this day. We haven't eliminated them, because as I said in another comment, every generation just dilutes the old issues, it doesn't solve them. And while I could spend my evening finding studies from various countries that attest to my view on this, I have spent about as much time as I desire to on this, so I will grant you that my evidence is on the level of 'trust me bro' -- with the slight caveat that many people within just my family and close circle of friends are involved in the medical field and all largely agree to this, and they are not all based in the US (which by the way, your point is very specific to. ACA is a US thing, western medicine spans a bit more than that.) It is entirely fair for you to call out that I have offered no real peer-reviewed evidence for my statements. I intend to offer a viewpoint of someone who has had extensive peripheral experience with medical professionals and has discussed this topic with them, and to offer some avenues of thought on how and why the data sets might be biased.