What is healthspan and how is it different from life expectancy?

Healthspan is the portion of life a person spends in relatively good health, maintaining physical and cognitive function, independence, and the absence of severe limitations due to illness. Lifespan is the length of life from birth to death. Therefore, two people can live the same 85 years but have completely different healthspans: one maintains independence almost until the end of life, while the other lives the last 15-20 years with significant disabilities and multiple chronic diseases. [1]

However, the concept of healthspan has an important limitation: there is still no single, generally accepted scientific definition or analysis that accurately predicts how many years of healthspan a given person has left. A 2025 systematic review found 187 published definitions of healthspan: some count it to the onset of a chronic disease, others to disability, loss of physical function, or the ability to independently perform daily activities. [2]

Healthspan should not be confused with the Healthy Life Expectancy (HALE) indicator, which the World Health Organization calculates for populations. HALE statistically estimates the number of years a person in a given population can expect to live in "full health," taking into account not only death but also years lived with illnesses and disabilities. It is a population model, not an individual countdown. [3]

Healthspan, lifespan, life expectancy, and longevity: what's the difference?

The main confusion arises because several related terms are often translated into the single word "longevity." In reality, they describe different things.

Term	What does it mean?	The main question
Lifespan	Actual life expectancy from birth to death	How many years did the man live?
Life expectancy	Statistically expected life expectancy for a population at current mortality rates	How many years on average can you expect to live?
Healthspan	The period of life in good health and with preserved function	How many years does a person live relatively healthy and independent?
Healthy Life Expectancy (HALE)	Population life expectancy adjusted for diseases and limitations	How many years of "full health" can you expect on average?
Longevity	Longevity as the ability or fact of living a long life	How long does a person or a population live?

Lifespan is the simplest of these metrics: it ends at the moment of death. If a person was born in 1950 and died in 2035, their lifespan would be 85 years. In modern biogerontology, the term is defined precisely as this: the chronological duration from birth to biological death. [4]

Life expectancy is fundamentally different. It is not a prediction of a specific person's date of death, but a statistical characteristic of a population based on age-specific mortality. For example, global life expectancy at birth in 2021 was approximately 71.4 years, according to WHO estimates. This does not mean that every person born that year is expected to live exactly that long. [5]

Healthspan adds health status and function to time. The question itself changes from "how many years?" to "how many of those years can a person live without significant illness, disability, or loss of independence?" This is why modern geroscience increasingly views increasing healthspan as a more meaningful goal than simply prolonging survival. [6]

Healthspan is not necessarily a life without diagnoses.

Having a chronic illness doesn't automatically mean a person's healthspan has ended. This is one of the most important nuances that gets lost in the popular definition of "disease-free years."

Let's imagine two people with hypertension. The first is receiving treatment, has normal blood pressure, exercises regularly, travels independently, works, walks several kilometers, and has no significant limitations. The second has suffered a stroke and requires assistance with everyday activities. Both are formally diagnosed with hypertension, but their functional health is fundamentally different.

This is why the single definition of healthspan has generated scientific controversy. A 2025 systematic review found that definitions use different endpoints: the onset of a chronic disease, disability, decreased physical ability, or a combination of several parameters. The authors found 187 separate definitions and concluded that the term is not yet standardized enough to directly compare the results of different studies. [7]

A 2026 Biogerontology editorial articulated this problem even more precisely: while the end of the lifespan is clear—death—the end point of the healthspan is much less certain. The author proposes focusing primarily on clinically significant loss of physical or mental independence, while simultaneously acknowledging that good function can be maintained even in the presence of disease. [8]

Therefore, for the average person, it makes more sense to understand healthspan not as “life with a completely clean medical record,” but as a period when the state of health allows one to largely maintain functions, independence, and participation in everyday life.

What exactly constitutes a good healthspan?

Healthspan is much broader than simply the absence of a heart attack or cancer. Modern clinical geroscience considers several interrelated domains: chronic diseases, physical function, cognitive abilities, frailty and disability, quality of life, and the ability to perform daily activities. [9]

Physical function refers not only to the presence of muscles but also to the ability to use them in real life. Walking speed, the ability to rise from a chair, climb stairs, maintain balance, and tolerate physical exertion can better reflect functional aging than a single laboratory test.

Cognitive function includes memory, attention, decision-making, and the ability to independently organize one's life. A person may not have a severe physical illness, but significant cognitive decline can significantly shorten the period of independent living.

Physiological reserve reflects how well the body copes with stress—an infection, surgery, a fall, or a period of forced immobility. Healthspan research considers the body's ability to recover from a stressor an important sign of healthy aging. [10]

Finally, health cannot be reduced entirely to medical diagnoses. In recent years, researchers have discussed the need to consider psychological well-being, social functioning, and subjective quality of life. A critical review in 2025–2026 points out that an overly narrow definition of healthspan as "absence of disease" may mistakenly consider someone with a well-controlled chronic condition to be automatically unhealthy. [11]

What is Healthy Life Expectancy and why is it not quite healthspan?

The World Health Organization uses the official measure Healthy Life Expectancy, or HALE. It is particularly useful for comparing countries and tracking public health over time. [12]

The WHO defines HALE as the average number of years a person could expect to live in "full health" if they were subject to the existing levels of mortality and morbidity in the population over their lifetime. In the calculation, years with illness or the consequences of injury are not simply discarded but weighted according to the degree of health loss. [13]

Therefore, HALE cannot be represented as an exact date:

“A person is healthy until the age of 62, but sick from the age of 63.”

At the individual level, it doesn't work that way.

For example, several years of life with moderate osteoarthritis do not necessarily translate entirely into "unhealthy years." The population-based calculation takes into account the degree of limitation and combines it with other diseases and injuries.

In this sense, HALE resembles an equivalent number of full-term healthy years, whereas healthspan in geroscience is often used as a more conceptual description of the period of preserved health and function.

How does lifespan differ from healthy lifespan today?

Global data clearly shows why interest in healthspan arose in the first place.

According to WHO estimates, before the COVID-19 pandemic, global life expectancy at birth increased from 66.8 years in 2000 to 73.1 years in 2019. Healthy Life Expectancy increased from 58.1 to 63.5 years over the same period. WHO notes that the increase in HALE lagged behind the increase in overall life expectancy: approximately 5.3 and 6.4 years, respectively, according to the organization's calculations. [14]

If you simply subtract one indicator from the other, the difference was about 8.7 years in 2000 and about 9.6 years in 2019.

Following the pandemic deterioration, global estimates in 2021 were about 71.4 years of life expectancy and 61.9 years of HALE, a difference of about 9.5 years.[15]

Year	Global life expectancy	Global HALE	Arithmetic difference
2000	66.8 years	58.1 years	≈8.7 years
2019	73.1 years	63.5 years	≈9.6 years
2021	71.4 years	61.9 years	≈9.5 years

The last column is easily misinterpreted. It does not mean that the average person necessarily spends the last 9.5 years of their life seriously ill. HALE is a population-weighted indicator: years and periods of life with varying degrees of impairment are mathematically summed. [16]

This is one of the most important points to understand about longevity statistics.

Can life expectancy increase faster than healthspan?

Yes. This is precisely one of the central problems of modern anti-aging medicine.

Let's imagine that new treatments allow a person to live significantly longer after a heart attack, stroke, cancer, or severe heart failure. Lifespan increases—and this is a huge medical achievement. But if a person simultaneously remains significantly limited by the disease, the increase in healthspan may be smaller.

The NIH Geroscience Interest Group explicitly notes that advances in the treatment of certain diseases have increased life expectancy, but this has not always been accompanied by a parallel increase in the period of good health. This is why geroscience addresses the issue not only of preventing death but also of delaying multiple age-related diseases and disabilities. [17]

The WHO finds the same phenomenon at the population level. Between 2000 and 2019, both the lifespan-like indicator life expectancy and HALE increased, but typical life expectancy increased somewhat more. [18]

This doesn't mean that modern medicine "doesn't do a good job of prolonging life." On the contrary, the ability to live after a disease that previously quickly ended in death is a success. The next challenge is to ensure that this additional time is accompanied by as little disability as possible and greater independence.

What is "compression of the period of illness"?

There is a separate concept for this: compression of morbidity.

The idea was formulated in detail by James Fries as early as 1980. He suggested that if the onset of chronic disease and disability could be delayed to a later age faster than life expectancy increased, then the period of significant illness before death would become shorter. [19]

Let's imagine two scenarios.

In the first, a person lives 82 years, and significant chronic limitations begin at 62. This results in a twenty-year period of varying degrees of illness or disability.

In the second, the lifespan remains the same—82 years—but serious functional deterioration begins only at 77. Formally, the person did not live longer, but their healthspan increased by approximately 15 years.

There's a third scenario: a person lives to 90, but serious limitations begin at age 62. Lifespan has grown significantly, while Healthspan has remained virtually unchanged.

This is why increasing life expectancy and increasing healthy life expectancy are related but not identical goals.

Modern global studies show that the picture varies across countries: increased longevity is not always accompanied by a proportional reduction in the period of illness and disability. In an analysis of 1990–2019, trends toward a decline in morbidity varied depending on the country's income level and baseline life expectancy. [20]

Is it possible to have good health with multiple chronic conditions?

Yes, if the conditions are well controlled and the person maintains functionality and independence.

This is especially important in older age, when multimorbidity—the presence of several chronic conditions simultaneously—becomes more common. The WHO emphasizes that older people often have several conditions simultaneously, but functional capabilities vary greatly even among people of the same age. [21]

For example, a 75-year-old person may have hypertension, hypercholesterolemia, and osteoarthritis, but live independently, exercise, travel, and maintain cognitive function.

Another person of the same age may formally have fewer diagnoses, but after a fall and prolonged immobility, they may experience significant loss of muscle strength, become unable to leave the house on their own, and require assistance.

If healthspan were defined solely as the number of years "before first diagnosis," the first person would automatically be unhealthy much earlier than the second. From a functional perspective, this conclusion seems dubious.

This is why a systematic review of healthspan definitions in 2025 showed such heterogeneity, and current publications suggest taking into account disease, disability, physical and cognitive function simultaneously. [22]

Healthspan and quality of life are not the same thing.

Quality of life, or quality of life, overlaps with healthspan, but is not synonymous with it.

Quality of life includes subjective assessment of physical condition, emotional well-being, social relationships, life satisfaction, and ability to engage in meaningful activities.

Healthspan is often measured more objectively: through the presence of diseases, disabilities, functional limitations, and physiological indicators.

This raises an interesting question. People with disabilities or chronic illnesses are capable of reporting a good quality of life, maintaining relationships, working, and maintaining subjective well-being. If healthspan is defined solely as "life without illness or disability," this reality is lost.

This is precisely the problem raised by contemporary criticism of healthspan: too narrow a biomedical model can underestimate the well-being and adaptation of people living with chronic illness or disability. [23]

Therefore, for clinical medicine, both the objective function and how a person himself evaluates the possibility of living the desired life are important.

Healthspan and biological age are different concepts.

Biological age is not a direct measurement of healthspan.

Modern "aging clocks" can use DNA methylation, blood proteins, metabolites, organ imaging, and other parameters to assess age-related biological changes. Some models are good at predicting disease and mortality and can potentially be used to assess the effects of future interventions. [24]

However, if a commercial test reports:

Calendar age - 55 years, biological - 49,

It is impossible to conclude from this:

"Healthspan lasted for six years."

Epigenetic age is a model biomarker. Healthspan is a clinically and functionally broader concept related to how long a person maintains good health.

The issue remains relevant in 2026. A systematic evaluation of clinical aging clocks found that only a small proportion of models had both low concerns about the quality of development and applicability, and the authors called for more attention to external validation of existing models. [25]

In August 2026, new data emerged on the response of the epigenetic clock to real-world interventions. Researchers pooled 51 intervention studies to test which clocks actually change with interventions associated with clinical benefit. This work is an important step toward creating a surrogate measure of aging, but the question of validation remains unresolved. [26]

Therefore, today it is impossible to replace the HealthSpan assessment with a single blood test or epigenetic test.

Is it possible to calculate your healthspan?

Definitely not. In clinical practice, there is no universal "healthspan calculator" that reliably determines the beginning and end of a specific person's healthy lifespan.

At the population level, the WHO can calculate HALE because it has vast data sets on mortality, illness, and disability. At the individual level, the problem is much more complex.

For individual assessment, it is much more useful to observe several real health trends:

• cardiovascular risk;
• blood pressure;
• glucose metabolism;
• lipid profile;
• presence and control of chronic diseases;
• physical activity;
• muscle strength;
• walking and balance;
• cognitive functions;
• ability to perform normal daily activities;
• dream;
• mental health;
• social function.

This is not a single "healthspan score," but a set of domains that, taken together, provide a much better description of the likelihood of maintaining independence.

In its current Healthy Ageing strategy, the WHO generally prefers to speak of intrinsic capacity—a person's internal physical and mental capabilities—and functional ability, that is, the ability to do what a person considers important. Current WHO programs assess healthy aging precisely as the interaction of a person's intrinsic capabilities with the environment. [27]

This is a much more meaningful approach than a single “biological age” number.

What cuts healthspan the most?

Healthspan typically reduces the same factors that increase the likelihood of premature death and age-related diseases: tobacco, physical inactivity, an unfavorable metabolic profile, poorly controlled blood pressure, diabetes, unhealthy diet, and other chronic risks.

But here an additional dimension appears: the factor may not kill a person, but it may significantly limit his function.

For example, severe osteoarthritis doesn't necessarily dramatically reduce lifespan, but it can significantly shorten the period of free mobility. Sarcopenia—the loss of muscle mass and especially strength—may not show up in a routine blood test, but it increases the likelihood of falls and loss of independence.

Hearing loss may have little immediate effect on survival but can greatly impact communication and daily life.

Therefore, WHO defines healthy ageing as broader than the fight against fatal diseases and includes maintaining functional capacity, environmental adaptation and access to health and social care. [28]

What really helps increase the likelihood of long-term healthspan

There's no proven pill that guarantees a certain number of years of lifespan. However, there are well-documented interventions that reduce the risk of disease and functional decline.

The National Institute on Aging identifies regular physical activity, good nutrition, adequate sleep, not smoking, managing alcohol, managing medical conditions, and taking care of mental health as components of healthy aging that are accessible to the individual. [29]

Physical activity is particularly valuable because it simultaneously impacts several healthspan domains: cardiovascular function, metabolism, muscle, ability to perform daily activities, and mental state.

Nutrition works differently. Its purpose is not to "rejuvenate cells," but to reduce the risk of malnutrition and disease. The current WHO 2026 recommendation is built around four principles: sufficiency, balance, moderation, and variety; the basis should be a variety of minimally processed foods, with limited free sugars, excess sodium, and unhealthy fats. [30]

Smoking cessation remains one of the most effective preventative measures, even in older age. The NIA emphasizes that quitting smoking is beneficial regardless of how long a person has smoked, reducing the risk of cancer, heart attack, stroke, and lung disease. [31]

Maintaining social connections is also becoming part of the modern understanding of healthy aging. In 2025, the WHO identified social isolation and loneliness as significant public health problems and included social connection in its global strategy. [32]

The main logic here is not in the search for a single “longevity habit,” but in maintaining several body systems in working order for as long as possible.

What's more important for healthspan: not getting sick or maintaining function?

Both, but with age the function takes on special significance.

In young adults, preventative medicine often focuses on preventing future illnesses: not smoking, maintaining physical activity, controlling blood pressure, weight, and metabolic factors.

In older age, another question is added to this: is a person able to use his health?

For example, laboratory results may be quite good, but if a person, after several months of immobility, has lost the ability to get out of a chair and walk independently, his functional health span has noticeably worsened.

This is why geroscience increasingly evaluates physical and cognitive function, frailty, disability, stress tolerance, and the ability to recover from illness alongside traditional diagnoses. [33]

Luigi Ferrucci and colleagues in aging research also emphasize that physical and cognitive function are strong predictors of adverse outcomes and that people of the same age vary greatly in their vulnerability to disease and disability. [34]

This explains why maintaining strength, mobility and independence becomes a central part of the healthspan idea.

Is it possible to increase healthspan without increasing lifespan?

Yes - as a concept it is quite possible.

If the intervention delayed the onset of disability from 65 to 75 years, but the person in both scenarios died at 85, the lifespan did not change, but the period of good health increased by about ten years.

This is precisely the result that corresponds to the concept of compression of morbidity: diseases and functional limitations are concentrated closer to the end of life. [35]

The opposite situation is also possible. Medical intervention prolongs the life of a person with a severe chronic disease, but does not significantly restore their function. Lifespan increases more than healthspan.

Finally, the ideal scenario is an increase in both indicators: serious diseases occur later, the person maintains function longer and simultaneously lives longer.

In geroscience research, it is the third option that is of particular interest: targeting fundamental aging mechanisms to simultaneously delay multiple diseases and functional decline. However, specialized pharmacological methods for increasing human healthspan are still in the clinical trial phase. [36]

Should we strive for maximum lifespan at any cost?

This is no longer just a biological question, but also a clinical and personal one.

For most people, the goal of medicine isn't to trade life expectancy for quality of life. Treating a heart attack, cancer, or infection can preserve both years of life and the quality of those years.

But in some situations—such as a severe, terminal illness—the decision may involve a balance between potential life extension, treatment side effects, functionality, and the patient's own priorities.

This is why modern medicine uses not only mortality but also indicators such as disability, quality of life, functional independence, and patient-reported outcomes. Geroscience reviews also suggest including these domains in studies of interventions aimed at healthspan. [37]

Therefore, healthspan does not replace lifespan. It adds to the question "can we extend life?" the next one: "what will this additional life be?"

Why is the concept of healthspan important for medicine?

Increased life expectancy has transformed the structure of medicine. Many diseases that once quickly led to death can now be controlled for years. This is a significant achievement, but at the same time, the number of people living with multiple chronic conditions has increased.

Geroscience proposes a change in the direction of research: instead of targeting each age-related disease only after its onset, we should instead try to understand the general biological processes of aging that increase the likelihood of multiple diseases. The NIH Geroscience Interest Group formulates the hypothesis precisely this way: by influencing the physiological processes of aging, it is possible to simultaneously delay several chronic diseases. [38]

This approach does not yet mean that there is a clinically proven “anti-aging” cure. Human studies of rapamycin, senolytics, and other candidates are ongoing, and developing appropriate healthspan endpoints remains a scientific challenge. [39]

This is why the definition of healthspan has more than just philosophical significance. Without a standardized endpoint, researchers find it difficult to answer the fundamental question:

Does the new intervention actually make lives healthier or just change a lab value?

What is often misunderstood

"Healthspan is the age at first illness."

Not necessarily. There is no single definition, and modern approaches increasingly consider not only the diagnosis but also significant disability, physical and cognitive function. A person with a well-controlled chronic condition can maintain a high level of independence. [40]

"HALE shows how many years a person will be sick at the end of their life."

No. The difference between life expectancy and HALE is not a literal uninterrupted period of illness before death. HALE mathematically accounts for years lived with varying degrees of health loss. [41]

“Lifespan and life expectancy are the same thing”

Not quite. Lifespan describes the lifespan of a particular organism; life expectancy is the statistical lifespan expected of a population at a given mortality rate. [42]

"Biological age is shown by healthspan"

No. The biological clock is potentially useful for risk assessment and aging research, but does not yet replace clinical assessment of health and function.[43]

"To increase health span, you need a special anti-aging product."

There is currently no proven drug that guarantees a healthy person's lifespan will be extended. The evidence base for chronic disease prevention, physical activity, proper nutrition, smoking cessation, and medical monitoring of risk factors is significantly stronger. [44]

"Healthspan is more important than lifespan"

This dichotomy oversimplifies the issue. Life is not less valuable because of a chronic illness, and treatments that prolong survival can have enormous medical value. Healthspan is needed to add function and quality to the assessment of years lived, not to eliminate the importance of life expectancy.

Practical: What to look at instead of trying to calculate your healthspan

It is more useful for a person to track several parameters that have clear clinical significance rather than looking for a single number.

If physical activity is gradually increasing, muscle strength is maintained, a person is able to walk confidently and perform daily activities, blood pressure and metabolic indicators are controlled, sleep is adequate, chronic diseases are treated, and cognitive and social activity is maintained, this is much more meaningful than the commercial claim "healthspan = 72 years."

It's especially important to notice trends. A rapid decline in strength, frequent falls, significant unintentional weight loss, memory impairment, a sharp decrease in exercise tolerance, or a loss of the ability to perform normal daily activities should not be automatically attributed to "normal aging."

These changes may be due to specific diseases, nutritional disorders, medication side effects, depression, cardiovascular, or neurological problems. In this situation, it's necessary to seek the cause of functional decline rather than measuring abstract biological age.

This approach is in line with the modern WHO Healthy Ageing concept: the main goal is to support a person’s ability to do what is important to him, rather than striving for the ideal absence of all diagnoses. [45]

Key points from experts

Andrea B. Maier, MD, PhD, FRACP, is a physician in internal medicine and geriatrics, a professor at the Vrije Universiteit Amsterdam, and a professor of medicine at the National University of Singapore. Her research focuses on aging and healthy longevity. Her current VU profile lists her professorships in Aging & Later Life and Ageing & Vitality, and the NUS Healthy Longevity program lists geriatrics and internal medicine among her research areas. [46]

In a 2025 systematic review, the Maier research group identified one of the central problems of the entire field: healthspan does not yet have a standardized definition. Among the 207 included publications, 187 contained a definition of healthspan, and these definitions varied significantly in terms of disease, disability, and functional endpoints. The authors believe standardization is necessary for the fair comparison of studies. [47]

Luigi Ferrucci, MD, PhD, is a geriatrician and epidemiologist, Scientific Director of the National Institute on Aging, and Senior Investigator of the Longitudinal Studies Section of the NIA. His research focuses on the mechanisms of gradual physical and cognitive decline, the development of frailty, multimorbidity, and disability with age. [48]

In a profile published by the NIA in June 2026, Ferrucci identified increasing quality and active life years as one of the central goals of modern aging science. His research program emphasizes the role of physical and cognitive function as indicators that can provide information about the state of the aging organism beyond the traditional list of diseases. [49]

Frequently Asked Questions

What does healthspan mean?

These are the years of life that a person spends in reasonably good health and with preserved independence. The precise scientific boundary of healthspan has not yet been standardized. [50]

How to translate healthspan into Russian?

The most commonly used expressions are "healthy life expectancy," "healthy lifespan," or "healthy lifespan." In scientific discussions, it is sometimes more convenient to use the English term, as its definition varies across studies.

What is the difference between healthspan and lifespan?

Lifespan represents the entire lifespan from birth to death. Healthspan describes the portion of life that occurs without significant illness, disability, or significant loss of function. [51]

How does healthspan differ from life expectancy?

Life expectancy is the statistical life expectancy of a population. Healthspan refers to the duration of a period of good health.

What is HALE?

Healthy Life Expectancy is the official WHO indicator that estimates the average number of years of life expected in “full health”, taking into account diseases and injuries. [52]

What is the average healthspan in the world?

There is no universal global figure for individual healthspan. The closest standardized indicator is the WHO HALE. In 2021, the global HALE at birth was estimated at approximately 61.9 years. [53]

Does this mean that after 61.9 years a person is no longer healthy?

No. This is a population-based statistical estimate, not an age limit for an individual.

How many years on average does it take between healthspan and death?

Such a figure cannot be obtained by simply subtracting HALE from an individual's life expectancy. The global arithmetic difference in 2021 was approximately 9.5 years, but this reflects the combined weighted impact of illness and disability, not the mandatory final 9.5 years of illness. [54]

Can a person with diabetes have good healthspan?

Yes. If the disease is well controlled, there are no complications, and the person maintains high physical and cognitive function, the diagnosis itself does not necessarily mean the end of a functionally healthy life.

Is it possible to increase healthspan after 60 years?

Yes, the likelihood of maintaining function can be improved even in older age. Physical activity, nutrition, smoking cessation, sleep, and chronic disease management remain important, no matter how ideal a lifestyle was previously. [55]

Is it possible to find out your healthspan from a blood test?

There is no single validated test. Even modern biological clocks remain a developing tool and are not equivalent to measuring healthspan. [56]

What is better - living longer or having a greater health span?

Medicine strives for both outcomes: living longer and maintaining health and function for as long as possible. The goal of healthy longevity is not to choose one over the other, but to narrow the gap between them.

Main

Lifespan answers the question "how long a person lives," while healthspan answers the question "how much of that life they maintain good health and functional independence." The concepts are closely related, but one does not guarantee the other: modern treatments can significantly prolong life, even if some of those extra years are spent with chronic diseases. [57]

However, healthspan cannot be reduced to the age of first diagnosis. A 2025 systematic review found nearly two hundred definitions in use, and publications from 2026 continue to debate the precise boundary between a healthy period and a period of functional decline. Therefore, it is more appropriate to assess not only the presence of disease, but also mobility, strength, cognitive function, independence, and quality of life. [58]

The global difference between life expectancy and HALE should also not be interpreted as the number of years of severe illness before death. The WHO calculates HALE as a weighted population indicator that takes into account varying degrees of health deterioration at different periods of life. [59]

For a person, the practical meaning of HealthSpan isn't about achieving a pretty number, but rather a different priority: not only avoiding early death, but also maintaining the ability to move, think, make decisions, live independently, and pursue meaningful activities for as long as possible. This is the transition from simple longevity to healthy longevity.