Women live longer on average than men. However, they also spend 25% more of their lives in poor health, which amounts to nine more years. And this largely occurs during their working years, not in old age. Here's what this number means, what's behind it, and what research says about how to change it.
The number that has shaped the debate about women's health since its publication at the World Economic Forum in Davos in January 2024 is: women spend 25% more of their lives in poor health than men.
The study comes from the McKinsey Health Institute in collaboration with the World Economic Forum. It was the first time that the extent of the so-called gender health gap was quantified globally and with such precision.
Women live longer on average than men. This was long considered proof that women are healthier or that the healthcare system adequately provides for them. The 25% figure completely refutes this assumption.
Living longer is not the same as living well. Women spend a disproportionate part of their longer lives in poor health, with limitations, and with chronic suffering that the healthcare system has consistently failed to prevent, detect, or treat.
This gap represents 75 million years of life lost each year due to poor health or early death. Closing it would give every woman in the world seven additional healthy days per year – over a lifetime, more than 500 days. And it would add over a trillion dollars annually to the global economy by 2040.
These are not wishful projections. These are the documented economic costs of what is already happening, measured in healthy years of life that women do not get.
Nine Years, and Most of It During Working Age
The average woman spends nine more years than the average man in poor health or with some form of limitation.
This figure is made even more impactful by another finding: approximately half of the healthy years that women lose occur between the ages of 20 and 60.
This is not a disease of old age. This is chronic suffering during the very decades when women are building careers, raising families, running businesses, and making the majority of healthcare decisions for everyone around them. The years of highest productivity, greatest aspirations, and most responsibility are lost.
The underlying diseases are neither rare nor biologically mysterious. These are conditions that affect hundreds of millions of women, have been documented for decades, and have received only a fraction of the research funding that would be commensurate with their prevalence.
PMS, endometriosis, menopause, migraines, pregnancy- and childbirth-related conditions, and cardiovascular diseases in women: these nine conditions alone account for one-third of the entire health gap.
PMS and menopause combined: conditions that affect practically every woman who reaches middle age received less than 1% of the research funding for the diseases behind this gap between 2019 and 2023.
What the Doctors Said When They Finally Got a Big Stage
In October 2025, the episode of The Diary of a CEO featuring Dr. Mary Claire Haver, Dr. Vonda Wright, Dr. Stacy Sims, and Dr. Natalie Crawford became one of the most shared conversations about women's health the media has ever produced.
What the doctors described was not a new discovery. It was a long-documented reality finally being spoken about on a stage large enough to reach those affected.
Women come to the doctor with serious symptoms and are told it's stress, anxiety, or just part of being a woman. Women with endometriosis wait an average of six to ten years for a diagnosis because their pain is normalized instead of being investigated. And women in perimenopause enter one of the most physically profound transitions of their lives – without preparation and without support, because the medical system has never developed suitable tools for this phase.
Dr. Wright described this as "Whiny Woman Syndrome." This refers to the well-documented pattern of attributing women's symptoms to emotional rather than biological causes. The result is delayed diagnoses, inadequately treated pain, and years of suffering that could have been addressed earlier if the symptoms had been taken as seriously as they would have been in a male patient.
This is not a marginal observation. It is a pattern so well-documented that it has a name. And the women who have experienced it immediately recognize the description.
Women with very serious illnesses get lost in the healthcare system for years. Sometimes they are told it's all in their head, when in reality, they are seriously ill.
The Three Causes Identified by WEF and McKinsey
The McKinsey Health Institute report names three structural causes for the health gap that apply across all diseases and global regions.
The first is a gap in science itself. Female biology is under-researched, women have been historically underrepresented in clinical trials, and the data basis for treatment decisions relies disproportionately on male data.
The second is a gap in care. Even where knowledge exists, it is not consistently applied. Women face greater barriers to accessing treatment, and their symptoms are more often dismissed or inadequately treated.
The third is a gap in data. For diseases affecting women, standardized measurement tools are less common. They are less frequently included in large epidemiological studies. And therefore, the evidence that would stimulate investment and political change is less often generated.
These three gaps reinforce each other. Inadequate science creates inadequate care. Inadequate care creates inadequate data. And inadequate data provides no arguments for better science.
This cycle has been ongoing for decades. Its result is the 25% figure: 25% more of a woman's life spent in poor health due to conditions that could be prevented or treated, or at least better understood, than the current system has allowed.
The Cellular Level Rarely Mentioned in the Debate
Public discussion about the health gap primarily revolves around research funding, clinical bias, and the absence of women in studies. All of this is real and important.
What is almost never mentioned is the cellular level: the fact that the fundamental biological processes that maintain women's health receive less and less support with age itself, specifically due to the decline of NAD⁺.
NAD⁺ is behind energy production, DNA repair, hormone synthesis, sleep regulation, immune function, and inflammation control. In every adult, its levels decline from the mid-20s. In middle age, it is only about half of its peak level.
In women, this decline parallels the hormonal changes of perimenopause and menopause. Both processes amplify each other's effects on health and performance.
The enzyme that produces progesterone needs NAD⁺ as a cofactor. Sirtuins, which regulate inflammation, need NAD⁺ for activation. And mitochondria, which supply energy to the cells of all tissues that change during menopause, need NAD⁺ to produce energy efficiently.
The cellular energy deficit due to NAD⁺ decline cannot be viewed separately from the health gap. It is one of the biological mechanisms underlying it, and it operates at a level that most clinical debates about women's health have never examined.
The women's health gap is a failure of research and a failure of funding. But it is also a failure of cellular energy supply, and no policy alone can solve that.
What It Would Take to Close the Gap
The action plan published by McKinsey and the World Economic Forum in January 2025 identifies what would be structurally necessary: more research specifically on female biology, better gender-disaggregated data, clinical guidelines that reflect female disease progression, and investments directed to where the disease burden is highest and research funding has been lowest.
The Gates Foundation has pledged $2.5 billion for this by 2030. The World Economic Forum has established the Global Alliance for Women's Health with over 120 member organizations. And every dollar invested in women's health is estimated to return approximately three dollars in economic growth.
At the individual level, closing the gap means that women gain access to information about their own biology that the current system has not reliably provided. This includes the cellular mechanisms behind their complaints, existing research on them, and products that were actually developed with their biology as a basis, not as an afterthought.
NMN is one of the few longevity interventions whose foundational human study was specifically conducted with women and measured results directly relevant to female metabolic health.
This precision is not the norm. It is what it concretely means to take biology seriously. And it is the minimum standard that women have always deserved.
The Seven Days That Matter
Closing the health gap would give every woman in the world seven additional healthy days per year. Taken alone, that sounds like little. Over a lifetime, it's 500 days. And across 3.9 billion women, it's 75 million healthy years of life that would be regained each year – for conditions that are already understood, already partially treatable, and chronically underfunded.
The 25% figure is not a law of nature. It is the documented price of decisions made by a healthcare system and a research establishment over decades. And it can be reversed by making different decisions. The momentum for this, in funding, in research, in public debate, has never been greater than now.
Women live longer. But they also spend more of those years in poor health than they should, losing the most productive decades of their lives to conditions that were never adequately researched, never adequately funded, and never adequately taken seriously.
That is the 25% figure. A number that should not exist and which a growing international alliance of researchers, doctors, and institutions is now trying to change. The question for every woman reading this is what she does in the meantime, while the system catches up with the biology it has overlooked for so long.
Sources
- McKinsey Health Institute & World Economic Forum. (2024). Closing the women's health gap: A $1 trillion opportunity to improve lives and economies. https://www.mckinsey.com/mhi/our-insights/closing-the-womens-health-gap-a-1-trillion-dollar-opportunity-to-improve-lives-and-economies
- McKinsey Health Institute & World Economic Forum. (2025). Blueprint to close the women's health gap: How to improve lives and economies for all. https://www.mckinsey.com/mhi/our-insights/blueprint-to-close-the-womens-health-gap
- McKinsey Health Institute. (2024, January 30). MHI unveils investment case for closing the women's health gap. https://www.mckinsey.com/about-us/new-at-mckinsey-blog/mhi-unveils-investment-case-for-closing-the-womens-health-gap
- Gates Foundation. (2025). Gates Foundation announces catalytic funding for women-centered research. https://www.gatesfoundation.org/ideas/media-center/press-releases/2025/08/womens-health-funding-commitment
- Haver, M. C., Wright, V., Sims, S., & Crawford, N. (2025, October 16). Hormone & fertility experts: We've been lied to about women's health. The Diary of a CEO with Steven Bartlett.
- World Economic Forum. (2025, January). There's a women's health gap: Here's how to close it. https://www.weforum.org/stories/2025/01/theres-a-womens-health-gap-heres-how-to-close-it/
- Yoshino, M., Yoshino, J., Kayser, B. D., et al. (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 372(6547), 1224–1229. https://doi.org/10.1126/science.abe9985
- Covarrubias, A. J., Perrone, R., Grozio, A., & Verdin, E. (2021). NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 22(2), 119–141.