A letter to the women in our lives, backed by the science they deserve
A Workout Conversation That Changed Everything
A few years ago, I was talking to a friend about training protocols. ATP energy systems, creatine pathways, workout structure. I was going on about how her workout should look, citing studies I'd read and protocols I'd tested on myself.
She stopped me mid-sentence. "My body doesn't sustain the same kind of energy throughout the rest of the month."
I felt ignorant. And I should have. I had been reading longevity research for years at that point. At Healome, we had built biological aging clocks, and we built different clocks for men and women, because the data demanded it. I knew, at a technical level, that sex mattered. But I had never once stopped to ask what it actually felt like to live in a body that operates on a fundamentally different hormonal rhythm than mine, one that changes energy availability, recovery capacity, and metabolic function across a monthly cycle.
That conversation stayed with me. Not because it was dramatic, but because it was so casually true. She wasn't citing a study. She was describing her lived experience. And no amount of longevity science I'd read had prepared me for it, because the research itself was built primarily on bodies like mine.
This article is about that blind spot in women's health. It is, in many ways, a letter. To my mother. To my friends. To every woman who has had to figure out her own health in a world where the science wasn't built for her. We don't have all the answers yet. But what we do have, we want to share with honesty, with care, and with the highest respect for what the evidence actually says.
The numbers tell the story clearly. Women experience adverse drug effects at twice the rate of men. Seven of 10 geroprotective drugs tested in the NIA Interventions Testing Program work better or only in males. Menopause accelerates biological aging as measured by epigenetic clocks. Two-thirds of Alzheimer's patients are women. And 80% of autoimmune diseases occur in women. These aren't niche findings. They describe a systematic gap in how we study aging.
The Male Default: How We Got Here
In 1977, the U.S. Food and Drug Administration issued a recommendation that would shape medical research for the next two decades: exclude "any premenopausal woman capable of becoming pregnant" from Phase I and early Phase II drug trials1.
The reasoning was protectionist. The thalidomide tragedy of the late 1950s and 1960s had caused over 10,000 birth defects in children of women who took the sedative for morning sickness. The FDA wanted to prevent a repeat. At-home pregnancy tests didn't exist yet in 1977.
But the definition of "childbearing potential" was extraordinarily broad: it included single abstinent women, women using contraceptives, and women whose partners had vasectomies. The FDA itself later described the guidance as "rigid and paternalistic."
In practice, drug companies interpreted the restriction even more broadly, limiting women's entry into later trial phases as well. For 16 years, the default research subject was male.
The NIH Revitalization Act of 1993 mandated the inclusion of women and minorities in federally funded trials. But gaps persist. An analysis of 1,433 clinical trials with over 300,000 participants found that, on average, only 41.2% of participants were female2. In industry-sponsored early-phase trials, the figure drops below 30%. During COVID-19, despite clear evidence that men and women had different infection rates, drug responses, and mortality risks, only 4% of clinical trials actively sought to recruit women.
The consequence of this history is measurable: women experience adverse drug effects at twice the rate of men3. Not because female biology is more fragile, but because drug dosages and protocols were derived from male-dominant studies.
Medicine has long treated women as "smaller men." The longevity field inherited that assumption.
The Drug Problem: When Longevity Interventions Don't Work for Half the Population
The NIA's Interventions Testing Program (ITP) is one of the most rigorous frameworks for evaluating compounds that might extend lifespan in mammals. It tests interventions across three independent sites simultaneously. The results have been striking, but not in the way most people know.
Of 10 agents tested that showed lifespan extension, 7 either only worked in males or worked markedly better in males. Nordihydroguaiaretic acid, aspirin, 17-alpha-estradiol, Protandim, and canagliflozin only extended lifespan in males. Acarbose and captopril worked markedly better in males. Only rapamycin extended lifespan more in females4.
Seven out of ten.
When I first learned this, I wish I could say I was shocked. Sadly, I wasn't. When you spend enough time in this field, you start to see the pattern. It doesn't make it acceptable. But it does make it understandable why we need to pay closer attention. If the interventions being tested as the most promising anti-aging compounds don't work equally for women, then the research pipeline needs deliberate, sustained attention to close the gap.
Women Live Longer. That's Not the Whole Story.
Women outlive men in 176 of 178 countries, both at age 5 and at age 50. That's the headline most people know.
Here's what they don't know: women spend a higher proportion of that longer life in poor health. More frailty. More disability. More chronic conditions. A systematic review of over 37,000 adults found that frailty index scores are consistently higher in women than men across every age group5.
Researchers call this the "male-female health-survival paradox." Women live longer but sicker.
Growing up, both my parents were athletes, volleyball players. I watched them age side by side. And I noticed something I couldn't explain at the time: my mother developed wrist and lower back issues years before my father did. Her body seemed to be on a different timeline. Not worse, not weaker. Just different. Different vulnerabilities, different patterns. I didn't have the framework to understand why. The science I've read since then offers some answers, and they matter.
The paradox isn't just an academic curiosity. It challenges the fundamental question longevity science is trying to answer. If we're measuring success purely by years lived, women are already winning. But if the goal is healthspan, the number of years lived in good health, then women face challenges that the field has barely begun to address.
How the Hallmarks of Aging Differ by Sex
The hallmarks of aging are often presented as universal. They're not. Nearly every hallmark shows sex-specific patterns.
Epigenetic Aging
At all ages, males have a higher epigenetically predicted biological age than females6. Boys start older, biologically speaking, and the gap persists.
But there's a critical inflection point: menopause. A landmark 2016 study by Dr. Morgan Levine (then at UCLA, now at Altos Labs) and Dr. Steve Horvath, professor of human genetics and biostatistics at UCLA, published in PNAS, was the first to demonstrate that menopause accelerates biological aging as measured by epigenetic clocks7. They tracked DNA methylation in more than 3,100 women across four studies, including the Women's Health Initiative.
The finding: a woman who enters early menopause at age 42 would, eight years later, be a full year older biologically than a woman who entered menopause naturally at age 50.
"The younger a woman is when she enters menopause, the faster her blood ages," Dr. Levine noted. "This could have implications for death and disease risk."
A 2025 UK Biobank study of 46,463 postmenopausal women went further. Researchers identified 115 metabolites associated with years since menopause and found that the metabolic signature explained 89.3% of the association between years since menopause and PhenoAge, one of the most validated measures of biological aging8.
Menopause doesn't just change hormone levels. It reshapes metabolic function in ways that accelerate biological aging across multiple biomarkers.
Immune Aging
Research led by Dr. Eladio Márquez at Yale School of Medicine found that men experience immunosenescence, the decline of immune function, approximately 5 to 6 years earlier than women9. Men show greater decreases in T and B cell populations and accumulate more senescent immune cells. Women retain stronger adaptive immunity with age: their T cells maintain better proliferative capacity throughout the aging process.
But this stronger immune system is a double-edged sword. 80% of autoimmune diseases occur in women. The same immune vigilance that protects women from infections and helps them respond better to vaccines also predisposes them to inflammatory conditions where the immune system attacks healthy tissue.
After menopause, something interesting happens: the incidence of autoimmune diseases in women decreases toward male levels, while chronic inflammatory disease increases. The immune system doesn't just age. It reorganizes around menopause in ways we're only beginning to map.
Telomere Length
Boys have shorter telomeres at birth than girls, and the disparity persists throughout life. Earlier menopause is associated with shorter leukocyte telomere length and higher coronary artery disease risk. Genetic variants in TERT, the gene encoding telomerase, have been linked to both earlier menopause and accelerated epigenetic aging10.
The Cardiovascular Shift
Cardiovascular disease is the leading cause of death in women. Not breast cancer. Not osteoporosis. Heart disease.
Young premenopausal women have significant protection against cardiovascular disease. But that protection fades after menopause. By age 80, women overtake men in CVD incidence11.
The mechanism is well-characterized. Estrogen decreases fibrosis, stimulates angiogenesis and vasodilation, enhances mitochondrial function, and reduces oxidative stress. The 2003 Women's Ischemia Syndrome Evaluation (WISE) study found that young women with estrogen deficiency faced a sevenfold higher risk of coronary artery disease.
The numbers for early menopause are sobering. A pooled analysis of individual patient data published in the Lancet Public Health found that women entering menopause before age 45 had a 50% increased risk of coronary heart disease (relative risk 1.50, 95% CI 1.28-1.76)12. Surgical menopause without estrogen therapy carries a 2.7-fold higher CVD risk, according to the Framingham Study.
This is why the menopausal transition is increasingly recognized as a critical window for cardiovascular monitoring and early intervention. Not 10 years after menopause. During it.
The Brain: Two-Thirds of Alzheimer's Patients Are Women
Nearly two-thirds of all people diagnosed with Alzheimer's disease are women. For years, the explanation was simple: women live longer, so they have more time to develop the disease.
That explanation is increasingly insufficient. Research now suggests the disparity is driven by biological, hormonal, and immunologic factors, not just longevity13.
Alzheimer's is more severe and progresses more rapidly in women. Women develop greater tauopathy, with more cognitive consequences. Neuroimaging studies show that biomarkers of preclinical Alzheimer's emerge during the menopausal transition itself, not decades later.
Estrogen plays a direct neuroprotective role. It reduces amyloid precursor protein processing, increases clearance of amyloid-beta, suppresses tau hyperphosphorylation, and prevents aberrant neuronal cell cycle re-entry. When estrogen declines at menopause, those protective mechanisms weaken.
The "timing hypothesis" for hormone therapy has emerged from this research. Estrogen therapy appears to be neuroprotective when initiated in perimenopausal women under 65, but may actually accelerate tau accumulation when initiated in women over 7014. The same intervention, different outcomes, entirely determined by timing.
A 2025 meta-analysis in the Lancet Healthy Longevity found no evidence that hormone therapy either increases or decreases overall dementia risk. But the timing nuance matters enormously. Estrogen is protective when it's available, but it's not something you can add back 20 years later and expect the same effect. The window matters.
This connects directly to what we covered in cognitive longevity: cognitive reserve and brain health are built over decades. For women, the menopausal transition is a period that deserves specific attention.
Bone and Muscle: The Cascading Loss
Estrogen doesn't just protect the heart and brain. It maintains the structural integrity of the musculoskeletal system.
Women are more susceptible to osteoporosis than men. After menopause, the decline in estrogen drives a dramatic reduction in bone mineral density. Men have stronger bones and experience less lifetime bone loss, though men who do develop osteoporosis are more likely to die from fracture-related complications15.
The muscle story runs parallel. Sarcopenia, the age-related loss of muscle mass and strength, affects both sexes but hits women harder. Women experience more severe reductions in both muscle and bone mass compared to men, driven by the hormonal shift at menopause. And there's cross-talk: estrogen deficiency alters the chemical signaling between bone and muscle cells, creating a cascading effect where bone loss accelerates muscle loss, and vice versa16.
This is why many clinicians now describe menopause as a musculoskeletal event, not just a reproductive one. The decline in estrogen doesn't affect one system. It affects the interconnected web of bone, muscle, cardiovascular, neurological, and immune function simultaneously.
Why This Matters for Everyone
I want to be clear about something. This article comes from a place of love and respect, not blame. I'm not pointing fingers at the researchers or institutions who built the field of longevity science. So much research has gone into studying male biology, and that research has benefited everyone. The hallmarks of aging, the metabolic health frameworks, the exercise science, the supplement evidence: these findings aren't invalidated by the fact that they were tested predominantly on men.
But they are incomplete.
The entire scientific community has an opportunity to grow in the direction of understanding female health better. And I believe that this research won't just help women. When we studied male biology deeply, it advanced medicine for all of humanity. Directing resources toward female biology will open new avenues for better health across society as a whole.
Menopause research is already doing this. The epigenetic clock insights from Dr. Levine and Dr. Horvath's work on menopause have advanced our understanding of biological aging clocks for everyone. The immune aging research that identified sex differences has deepened our understanding of inflammation and immunosenescence in ways that apply to both sexes.
The Vacuum That Unproven Science Fills
There's something else that frustrates me. Because female health has been under-researched, a vacuum exists. And that vacuum gets filled by people selling snake oil, lunar cycle protocols, astrology-based health plans, and other unproven approaches marketed specifically to women.
I understand the appeal. When the official science doesn't have answers for your body, you look elsewhere. That's a rational response to an irrational situation.
But it means women are disproportionately targeted by health misinformation. And the solution isn't to dismiss their search for answers. The solution is to do better science and to communicate what we do know with honesty.
Whatever your spiritual, religious, or personal beliefs are, they are yours, and they matter. But you also deserve access to accurate, evidence-based knowledge about your own biology. The two aren't in conflict. Our role, as we see it, is to make sure the science is available, clearly communicated, and free of the hype that has plagued too much of the wellness space.
Practical: Where to Start
If a woman in her late 30s or 40s came to me and asked, "I'm approaching menopause and I want to age well. What should I be paying attention to?" I'd be honest. I'd say: I'm not a doctor, and the first thing I'd recommend is finding a good functional medicine practitioner who understands female biology across the lifespan. Someone who will listen to you and treat you as a whole person, not a collection of symptoms.
But from a first-principles standpoint, the science keeps pointing to the same foundations:
Get your sleep. Sleep quality becomes especially important around the menopausal transition. Postmenopausal women with five insomnia symptoms were nearly two years older biologically than those without. Sleep isn't a luxury. It's recovery.
Get your exercise. Resistance training is one of the most effective interventions available for attenuating age-related bone and muscle loss. The evidence is strong, and it becomes more important as estrogen declines.
Eat your vegetables. This sounds simple because it is. The research on nutrition and longevity applies to everyone, but the metabolic shifts around menopause make nutritional quality even more relevant for women.
Pay attention early. The menopausal transition is a window, not just for hormonal change, but for cardiovascular monitoring, bone density baselines, and conversations about hormone therapy timing. Don't wait until menopause is behind you. The science suggests that the perimenopause window is when attention matters most.
Talk to your doctor about hormones. The timing hypothesis matters. If hormone therapy is being considered, the research suggests that earlier initiation (during perimenopause) may carry different risk-benefit profiles than later initiation. This is a conversation to have with a knowledgeable healthcare provider. Not to navigate from blog posts, not from wellness influencers, and not from us.
Ask about sex-stratified results. When you read about a longevity intervention, ask: was this tested equally in men and women? Were results reported separately? If not, the evidence may not apply equally to you.
Frequently Asked Questions
Why do women experience adverse drug effects more often than men? Most drugs were developed and dosed based on clinical trials with predominantly male participants. Women metabolize many drugs differently due to hormonal cycles, body composition, and enzyme activity. The result: women experience adverse drug effects at roughly twice the rate of men.
Does menopause actually accelerate aging? Yes, according to epigenetic clock research. A 2016 PNAS study by Dr. Morgan Levine and Dr. Steve Horvath found that menopause accelerates biological aging. Women who enter menopause earlier age faster biologically. A 2025 UK Biobank study of 46,463 women confirmed that menopause-associated metabolic changes explain 89% of the association with PhenoAge acceleration.
Why are two-thirds of Alzheimer's patients women? The disparity goes beyond the fact that women live longer. Research points to biological factors: estrogen plays a direct neuroprotective role, and when it declines at menopause, those protective mechanisms weaken. Neuroimaging shows preclinical Alzheimer's biomarkers emerging during the menopausal transition itself.
What can women do to age well around menopause? From a first-principles standpoint: prioritize sleep, resistance training, and nutritional quality. Establish cardiovascular and bone density baselines during perimenopause. Have a conversation with a knowledgeable healthcare provider about hormone therapy timing. The research suggests the perimenopause window is when attention matters most.
Why did Longevity Science Daily create a Women's Health lens? Because it was absent. Female biology follows distinct aging trajectories across epigenetic, immune, cardiovascular, musculoskeletal, and neurological systems. Treating women's health as a subcategory of general health misses patterns that affect half the population.
What This Means for Us
This is the first article in our Women's Health lens. We didn't create it because women's health is a niche topic. We created it because it was absent, and that absence was something we could no longer look past.
I want to be honest with you. We don't have all the answers. The research on female-specific aging is still catching up to decades of male-default science. There are gaps in what we know, and we won't pretend otherwise.
But what we do have, we are committed to publishing with authenticity, with forthrightness, and with the highest ethical standards we can hold ourselves to. No hype. No oversimplification. No pretending the evidence says more than it does. If the science is uncertain, we'll say so. If the data is strong, we'll share it with the context it deserves.
When I think about the women in my life, my mother, my friends, the women who have shaped who I am, it would mean a lot to me if anything we publish here can be of even a small benefit to them. Aging gracefully isn't something that belongs to one sex. It belongs to both. And understanding female biology better is part of how we get there for everyone.
This work matters to me personally. Not just as a researcher or a publisher, but as someone who wants to leave the world in better hands than he found it. If even one woman reads something here and feels seen by the science, feels that someone took the time to ask the right questions about her biology, then we're moving in the right direction.
We really care about this. And we hope that shows, not just in this article, but in everything that follows.
This is the first article in our Women's Health series in Understanding Aging. Related: The 12 Hallmarks of Aging | Inflammation and Aging | Your Body's Biomarkers
Written with the help of AI tools, shaped and verified by humans who care about getting this right.
Nothing here is medical advice. The information provided is for educational purposes only. Consult with your healthcare provider before making any changes to your health regimen.
Footnotes
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Women's involvement in clinical trials: historical perspective and future implications. Pharmacy Practice, 2016. PMC4800017; History of Women's Participation in Clinical Research. NIH Office of Research on Women's Health. ORWH ↩
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Women are poorly represented in clinical trials. Nature, 2025. Nature ↩
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The gender gap in clinical trials. Labiotech, 2024. Labiotech; Why we know so little about women's health. AAMC. AAMC ↩
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Sex Differences in Mouse Longevity and Responses to Geroprotective Drugs. GeroScience, 2023. PMC10751369 ↩
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The Male-Female Health-Survival Paradox. In: Sociality, Hierarchy, Health: Comparative Biodemography. National Academies Press. NCBI ↩
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Hägg S, Jylhävä J. Sex differences in biological aging with a focus on human studies. eLife, 2021. eLife ↩
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Levine ME, Lu AT, Chen BH, et al. Menopause accelerates biological aging. PNAS, 2016;113(33):9327-9332. PNAS ↩
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Years since menopause and its metabolomic signature with biological aging in women at midlife. npj Aging, 2025. Nature ↩
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Márquez EJ, et al. Sexual-dimorphism in human immune system aging. Nature Communications, 2020. Nature ↩
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Age at Menopause, Leukocyte Telomere Length, and Coronary Artery Disease in Postmenopausal Women. Circulation Research, 2024. AHA ↩
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Menopause Transition and Cardiovascular Disease Risk. Circulation (AHA Scientific Statement), 2020. AHA ↩
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Age at natural menopause and risk of incident cardiovascular disease: a pooled analysis. Lancet Public Health, 2019. Lancet ↩
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Estrogen, menopause, and Alzheimer's disease: understanding the link to cognitive decline in women. Frontiers in Molecular Biosciences, 2025. Frontiers ↩
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Menopause hormone therapy and risk of mild cognitive impairment or dementia: a systematic review and meta-analysis. Lancet Healthy Longevity, 2025. Lancet ↩
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Insights and implications of sexual dimorphism in osteoporosis. Bone Research / Nature, 2024. Nature ↩
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Research progress on the correlation between estrogen and estrogen receptor on postmenopausal sarcopenia. Frontiers in Endocrinology, 2024. Frontiers ↩