1. Introduction
The goal of extending human healthspan (the time we spend living healthy, free from serious disease) cannot be achieved without completely understanding the biological differences between men and women as they age.
Women live on average 5 years longer than men globally, meaning they have a longer overall lifespan. However, they often spend a larger proportion of their years dealing with chronic illness, disability, and frailty. Women spend roughly 25% longer in poor health than men. Understanding why women live longer but spend more time in poor health than men is one of the most important open problems in biology and economics alike.
Women represent the majority of healthcare spending in midlife, are the majority of caregivers, and the majority of the population over 80.
Yet most "geroprotective" trials (drugs or interventions designed to slow aging) remain sex-biased. In a systematic review of pharmacological lifespan and healthspan studies in mice, 40% of longevity studies used only male subjects or failed to report sex at all, and among those that did test both sexes, nearly 73% showed sex-specific results. Because the biology of aging differs between males and females, a single "one-size-fits-all" approach to longevity interventions is unlikely to work.
This also means something more troubling: if almost three-quarters of interventions tested do behave differently in males and females, then every male-only or sex-unreported study effectively blinds the field to critical biological signals. Sex-specific benefits may be missed, sex-specific risks may go unrecognized, and interventions that appear ineffective in mixed datasets may, in fact, work extraordinarily well for one sex.
In other words, by failing to study females, we are actively filtering out meaningful discoveries: obscuring mechanisms unique to women, distorting our understanding of the aging process, and slowing the development of targeted, effective longevity therapeutics for both sexes.
2. Female Biology as a Natural Laboratory of Resilience
Longevity research has largely been built on male physiology, even though men age faster and have shorter lifespans. This narrow focus limits our understanding of what drives long-term health. Studying female biology more deeply could reveal mechanisms that support longer lives. Across nearly every species, females live longer and sustain stronger immune defenses than males. They mount more durable responses to infection, recover more effectively from cellular stress, and show slower molecular aging by nearly every biological measure. Even at the chromosomal level, women carry a molecular safety net: two X chromosomes allow for genetic backup.
Indeed, from a scientific standpoint, female biology offers a natural laboratory of resilience. Female biology isn't static; it's rhythmic and adaptive. Across the lifespan, women's bodies undergo repeated cycles of transformation (monthly hormonal changes, for many pregnancy, and for all the transition through menopause), each involving major shifts in hormones, metabolism, and tissue renewal. The uterus alone regenerates its lining roughly 400 times in a lifetime. These processes are evidence of built-in resilience and repair. Better understanding those mechanisms could reveal levers of longevity that male-centric models have missed. Meanwhile, men tend to start showing molecular signs of aging earlier and decline faster across many tissues. The fact that research on ageing relies on a male blueprint (a model built around the idea that the body changes slowly and predictably over time) shapes how we measure and think about ageing: as a steady decline, something that can only be slowed, not actively repaired.
Aging is not a neutral, uniform process that plays out identically across bodies. It is biologically sex-specific from the molecular level upward. Hormonal environments shift differently; immune systems age along distinct trajectories; metabolic pathways diverge; even the brain's aging arc is sex-modulated. These differences shape how diseases emerge, how fast they progress, which biomarkers are meaningful, and which interventions actually work.
And so, in a century defined by ageing populations and escalating health costs, it makes little sense to leave half of human biology on the table. The path to longer, healthier lives for everyone will not come from erasing difference, but from learning how each body endures (and applying those lessons to all): a bi-directional model (one that studies how each sex resists, repairs, and recovers differently, and uses those insights to strengthen both).
Since men and women age differently, a powerful strategy would be to:
- Isolate the highly effective, natural defense mechanisms found in one sex.
- Develop highly specific, targeted therapies to give those benefits to the opposite sex.
3. Rethinking the Baseline: Changing Biomarker Thresholds
When we talk about extending healthy lifespan, much of the field depends on biomarkers that act as proxies for aging. Instead of waiting decades to see who lives longer, scientists watch what happens to numbers like D-dimer (clot turnover) or Lp-PLA₂ (inflammation inside artery walls). These markers are used to judge whether an intervention "slows aging."
But those baselines are mostly built on male data. One notable example is cardiovascular risk.
3.1 How Cardiovascular "Risk Scores" Are Built (and Why They Fall Short)
When clinicians estimate a patient's risk of heart disease (for instance, by saying "your 10-year risk is 3%"), they are not observing pathology directly but applying a statistical model. The most widely used of these is the Framingham Risk Score (FRS), first developed in the mid-20th century from the Framingham Heart Study, a landmark longitudinal cohort in Massachusetts that shaped modern cardiovascular prevention. Later tools, such as the ASCVD Pooled Cohort Equations, are direct descendants of this model.
However, these foundational datasets were predominantly white. The Original Cohort recruited 5,209 participants (2,336 men and 2,873 women) in 1948, though the population was almost entirely white and recruited from a single Massachusetts town. Their equations defined "normal" and "risk" based on this cohort, weighting variables such as cholesterol, blood pressure, smoking, and diabetes according to how they predicted outcomes in this population. Contemporary analyses have shown that, although sex-specific coefficients were later introduced, the underlying baselines and variable weightings may not fully capture sex-specific cardiovascular risk patterns.
3.2 Why Recalibration Matters
Consider two 55-year-olds, a man and a woman, with identical cholesterol, blood pressure, and D-dimer values.
Under current cut-offs, the man's D-dimer might be flagged as elevated, while the woman's would appear "normal," even though evidence suggests women (particularly after menopause) have naturally higher baseline D-dimer and distinct patterns of micro-clotting and endothelial activation. The algorithm therefore underestimates the woman's true vascular risk, delaying preventive action.
Conversely, transient hormonal changes (such as peri-menopausal rises in D-dimer or Lp-PLA₂) may be misinterpreted as pathology if male thresholds are applied, producing false positives and unnecessary treatment.
Recalibrating these models would mean rebuilding "normal" from the ground up:
- Establishing sex-, age-, and hormone-stage-specific reference ranges for inflammatory and vascular biomarkers
- Retraining risk algorithms on sex-balanced data
- Weighting variables differently where biology diverges
New models could detect female-specific early warning patterns (for example, rising D-dimer coupled with low-grade endothelial inflammation) long before conventional thresholds trigger concern. They would also refine how longevity trials interpret success, preventing conclusions about "universal" anti-aging effects that actually reflect male physiology.
4. Female Strengths: Pathways to Extend Men's Healthspan (F-to-M Translation)
4.1 Brain Health
As men and women age, their hormones, immune systems, and even the way their cells handle inflammation and repair change in different ways. These differences are especially pronounced in women around menopause, when shifting hormone levels alter metabolism, blood-vessel function, and brain signaling.
New research shows that female brains may activate unique protective pathways with age. Studies in both mice and human brain tissue suggest that one of the two X chromosomes (normally silent in female cells) can partially "wake up" in certain brain regions. This reactivation includes a gene called PLP1, which helps maintain myelin, the protective coating around nerve fibers that keeps electrical signals moving efficiently.
Why This Matters for Longevity: In aging female brains, PLP1 levels rise, possibly as a natural repair response. When scientists increased PLP1 activity in the memory centers of aging mice (in both sexes), the animals showed better learning and memory performance. The takeaway: women's hormonal and genetic biology may contain built-in repair mechanisms that protect the brain with age. To extend healthy lifespan for everyone, medicine needs to study and harness these mechanisms, not average them out.
4.2 Cellular Power Plants & Estrogen
Every cell in the body contains tiny "power plants" called mitochondria, which convert nutrients into usable energy. As we age, these power plants gradually lose efficiency, producing less energy and more waste in the form of reactive oxygen molecules.
One of the body's strongest natural protectors of mitochondrial health is estrogen, the primary female sex hormone. These effects help explain why, before menopause, women often maintain stronger metabolic flexibility and lower early risk for certain metabolic and cardiovascular diseases.
Estrogen regulates mitochondrial quality control through multiple pathways, including mitophagy (the recycling process that clears away worn-out mitochondria before they cause harm). Estrogen activates mitochondrial autophagy through pathways including the SIRT1/AMPK/ULK1 axis and PI3K/AKT signaling. In simple terms, estrogen helps cells identify and remove their "broken batteries," maintaining healthier energy output as we age.
Why This Matters for Longevity: Mitochondrial decline isn't the single cause of chronic disease, but it is a shared amplifier (worsening inflammation, vascular damage, and tissue repair failure across many conditions, from heart disease to dementia). Because mitochondria power nearly every organ, protecting their function supports every other system. Men have estrogen receptors too, but with far lower circulating estrogen. Researchers are developing targeted drugs that mimic estrogen's mitochondrial benefits without affecting hormones directly.
4.3 The Endothelium: Where Vascular Aging Begins
Every blood vessel in the body is lined by a thin layer of cells called the endothelium: a living interface that constantly regulates how vessels expand, contract, and communicate with the immune system. When it functions well, it keeps blood flowing smoothly and prevents inflammation. When it falters, it becomes the first domino to fall in cardiovascular and neurovascular aging.
One of its key regulators is a signaling molecule called endothelin-1 (ET-1). ET-1 acts like a master switch: it can either tighten blood vessels or relax them, depending on which receptor it binds to.
Why This Matters for Longevity: These differences help explain why vascular aging often accelerates after menopause and why protecting endothelial health is central to preventing both heart and brain disease. Researchers are now testing drugs that rebalance this system (either by boosting ETB signaling or blocking ETA overactivation). These strategies, already used in pulmonary hypertension, could eventually be adapted to slow vascular aging in both sexes.
5. Male Strengths: Pathways to Extend Women's Healthspan (M-to-F Translation)
5.1 The Musculoskeletal System: Muscle Aging and the Hormonal Shift
Muscle isn't just about strength (it's an essential organ of metabolism, mobility, and independence). When we lose muscle, we lose energy, balance, and the ability to recover from illness. Age-related muscle loss, known as sarcopenia, is one of the most direct predictors of frailty, falls, and long-term care needs.
The Challenge: Anabolic Resistance. Sarcopenia affects everyone with age, but its functional impact is greater in women because they begin adulthood with less muscle mass and strength. After menopause, the rapid loss of estrogen accelerates muscle decline.
The Search for Safer Solutions. Systemic testosterone therapy can increase muscle mass in women but carries side effects. Researchers are developing Selective Androgen Receptor Modulators (SARMs) (experimental compounds that turn on the muscle- and bone-building effects of androgens without affecting reproductive tissues).
5.2 The Genetic System: DNA Stability and Cellular Repair
Every cell's health depends on the integrity of its DNA. Over time, DNA accumulates tiny breaks and chemical errors. This gradual wear and tear (called genomic instability) is one of the universal hallmarks of aging.
Sex Differences in DNA Repair During Aging. The most striking finding is that men and women age differently at the cellular level. Recent studies analyzing DNA double-strand break repair in human blood cells revealed that repair pathways change in opposite directions for men and women with age.
6. Female Life Events as Predictive Stress Tests
6.1 Menopause as a "Time Accelerator"
Menopause is a biological stress test that reveals how quickly the body is aging. When estrogen levels fall, nearly every system that depends on energy balance, repair, or inflammation control is affected. Epigenetic clocks show this shift clearly. Both natural and surgical menopause are linked to a measurable acceleration of biological aging, often moving the body's molecular clock forward by several years.
This makes menopause a critical window for prevention: a moment when metabolic and molecular aging briefly accelerate, but can still be slowed or reversed with targeted intervention.
6.2 Pregnancy as a Sentinel Event
Pregnancy is one of nature's most powerful stress tests (a live demonstration of how the cardiovascular and metabolic systems handle extreme demand). During pregnancy, blood volume rises by approximately 30-50%, the heart works harder, and insulin sensitivity shifts dramatically. For most women, these changes are reversible. But when the system struggles to adapt, conditions like gestational diabetes or preeclampsia emerge. These complications are not isolated pregnancy events (they are early warning signs that the body's vascular system is under strain and may be more prone to chronic disease later in life).
7. Immunology and Strategic Lessons
The immune system is one of the clearest examples of biological divergence between men and women. Women's immune systems are generally more reactive: they clear infections faster and respond more strongly to vaccines. But that same vigilance comes at a cost (a higher risk of autoimmune diseases).
Men's immune systems age earlier. They lose infection-fighting "naïve" T cells sooner and develop higher levels of chronic, low-grade inflammation.
Pregnancy: Nature's Precision Immunotherapy. Pregnancy offers a remarkable model for how the body can fine-tune its immune response, tolerating one kind of "foreign" tissue (the fetus) without turning off systemic defense. Understanding how this system works could revolutionize how we treat chronic inflammation and autoimmunity in aging.
Androgen-Mediated Immune Modulation. Men's immune systems have their own built-in regulatory mechanism: androgens (male sex hormones) directly dampen certain inflammatory cell types. This localized anti-inflammatory effect may help explain why some autoimmune and allergic conditions are less common or less severe in men.
8. Conclusion: From Evidence to Engineered Longevity
Longevity science has reached an inflection point. The evidence is unambiguous: aging unfolds along sex-specific biological axes, and interventions that "work on average" often diverge by sex in both magnitude and mechanism. Persisting with male-centric models and sex-neutral thresholds guarantees quiet miscalibration whose costs compound across women's lives and national health expenditures.
This paper argues for a decisive shift: treat biological sex and hormonal state as first-order design variables in how we measure, model, and modify aging. Doing so is not a matter of fairness alone; it is the shortest route to accuracy and impact.
If the goal is healthspan for all, the path runs through precision. And the most reliable map we have is the biology that already outperforms. Study women—not as an afterthought, but as the organizing framework—and we will discover levers of aging that generalize across sex while finally delivering care that is calibrated, timely, and effective for the people who live longest.
About
About the Author: Oriana Kraft
Oriana Kraft is the founder of FemTechnology and creator of ORI, a new infrastructure layer for women’s healthcare. Trained in medicine and engineering at ETH Zurich, she began mapping the systemic gaps in women’s health as part of her thesis, work that evolved into the FemTechnology Summit, now a global convening platform spanning more than 60 countries and sectors across research, biotech, clinical care, and industry.
About FemTechnology
FemTechnology is building the future of women’s healthcare by addressing the gender health data gap and connecting innovation across the ecosystem.
About ORI
ORI combines structured clinical intake, rules-based logic, and adaptive AI to deliver precision care guidance built for women. Learn more at: www.ori.care