Biomarkers of Aging, Why Lifestyle and Function Trumps Molecules for Healthy Longevity
- Alastair Hunt
- 9 hours ago
- 8 min read
With an ageing global population, understanding how and why we age has become more than just a scientific curiosity - it's a public health priority. A recent social media post from Prof. Nir Barzilai highlighed a review by Furrer and Handschin arguing that while molecular research into ageing is expanding rapidly, we may be overlooking the most powerful tools already at our disposal: simple, functional measures of how well our bodies work.
These physiological biomarkers, they contend, are not only robust predictors of health and lifespan but are also ready for use now - unlike their molecular counterparts. In this article we will review the key issues that they contend must be addressed for health aging and longevity.
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
Why Biomarkers Matter
Aging is the strongest known risk factor for chronic diseases, frailty, and mortality. To slow ageing or extend healthspan (the years lived in good health), scientists need reliable ways to measure biological age - how “old” a body is functionally, rather than chronologically. However, no consensus exists on a perfect molecular marker of ageing. Many tools, such as epigenetic clocks or telomere length, show promise but lack consistency and proven relevance in humans.
"Lifestyle, behavioral, and environmental factors have a significant effect on human health and mortality, whereas many pharmacological and interventional approaches found in preclinical models still await human translation."
In contrast, physiological biomarkers - like cardiorespiratory fitness, muscle mass, strength, gait speed and daily physical activity - are established, measurable, and consistently predictive of outcomes like disease risk, frailty, and death. What is ageing? Learn more..
The Limits of Molecular Markers
The review highlights a gap between laboratory findings and human outcomes. Many ageing theories and potential anti-aging drugs have been based on animal studies using model organisms like mice, worms, or yeast. Yet these creatures have vastly different lifespans, metabolisms, and environmental exposures compared to humans. Promising compounds - resveratrol, metformin and rapamycin - have yet to show safe and reproducible anti-ageing effects in people.
Molecular ageing clocks, such as those based on DNA methylation, show changes with age but do not consistently predict health or mortality. They can also vary with temporary conditions like infection or stress, making them unreliable for real-world application at this stage.
Functional Fitness as the Gold Standard
If one lesson emerges clearly from the review, it’s this: ageing is not best measured by molecular decay or laboratory tests, but by what a person can still do. In this context, functional fitness - how well we move, lift, breathe, and navigate daily life - is a more reliable marker of biological age than any genetic or biochemical clock currently available. These physical capacities don’t just reflect our health; they shape it, influencing everything from fall risk to independence to life expectancy.
The authors place particular emphasis on cardiorespiratory fitness, often assessed by measuring VO₂max - the maximal amount of oxygen the body can utilise during intense exercise. VO₂max declines steadily with age, dropping by roughly 7 to 10% per decade after early adulthood. Critically, it’s not just a performance statistic for athletes; VO₂max is one of the strongest independent predictors of all-cause mortality in both healthy individuals and those with chronic conditions. Even modest improvements, regular cardio as recommend by health authorities, are associated with an 11 to 17% reduction in mortality risk. This improvement is attainable through just a few months of consistent moderate exercise, making it one of the most impactful and accessible interventions available.
But fitness isn't only about endurance. Muscle strength and power, particularly in the legs and hands, are equally vital. Grip strength alone is a powerful predictor of future disability, frailty and death. Loss of strength - sometimes described as dynapenia - often precedes declines in muscle mass (sarcopenia), and the combination of the two can severely limit mobility and resilience. Unlike lab-based tests that offer abstract numbers, a decline in strength is tangible: it might mean no longer being able to carry shopping bags, rise from a chair, or catch oneself during a stumble. Learn more about power.
Gait speed, another simple yet telling marker, reflects integrated function across the neuromuscular, cardiovascular and skeletal systems. Slower walking speeds are associated with increased risk of dementia, hospitalisation and mortality. Alarmingly, gait speeds below 1.0 to 1.2 metres per second may not be fast enough to safely cross a street at a pedestrian crossing, underscoring how physical decline can erode independence long before clinical illness is diagnosed.
Perhaps the most hopeful insight from this body of evidence is that all these functional biomarkers are modifiable. Regular physical activity - especially a blend of endurance, strength, balance and flexibility training - can preserve and even restore these capacities well into old age. Improvements in VO₂max, muscle strength, and mobility are achievable at any age, and carry with them reduced risk of chronic disease, improved mental health, and better quality of life. Even individuals in their 70s, 80s, or beyond can benefit significantly from structured exercise, often reversing frailty and regaining independence.
The review makes a compelling case that these physical measures should be prioritised in clinical and public health settings - not just as risk predictors, but as targets for intervention. Unlike molecular biomarkers that remain experimental, functional fitness is easy to assess, inexpensive to track, and highly responsive to lifestyle changes. These qualities make it a practical, powerful tool for anyone looking to monitor their ageing process and take meaningful action to stay healthy.
Nutrition and Ageing: What Really Matters
Among the most powerful yet often overcomplicated tools in the pursuit of healthy ageing is diet. While numerous dietary protocols have been promoted for their supposed longevity benefits - ranging from intermittent fasting to plant-only eating - the scientific evidence remains clearest when it comes to balanced, sustainable nutrition. The review underscores that a calorie-controlled, nutrient-rich diet is fundamental. Excess calorie intake, particularly from ultra-processed or sugar-laden foods, is strongly linked to chronic conditions such as diabetes, cardiovascular disease, and metabolic dysfunction - all major accelerants of biological ageing. However, severe calorie restriction, which extends lifespan in rodents, is unlikely to be beneficial or even safe for most humans, especially when it leads to malnutrition or loss of muscle mass. What does healthy caloric restriction look like? Learn more here.
Older adults, in particular, need to pay close attention to protein intake. Ageing is accompanied by anabolic resistance, meaning the body becomes less efficient at building and maintaining muscle. To counteract this, higher-than-standard protein consumption - often suggested at 1.2 to 1.5 grams per kilogram of body weight per day - is advised, especially when paired with resistance exercise. This combination helps maintain strength and mobility, reducing the risk of falls, frailty and loss of independence. High-protein diets are also being reconsidered for people with chronic kidney disease, as new research suggests they may still be beneficial when carefully managed.
Whole foods should form the core of any age-supportive diet. Eating patterns that resemble the Mediterranean diet - rich in vegetables, legumes, whole grains, moderate fish and dairy, and healthy fats like olive oil - consistently correlate with better health outcomes and lower rates of cognitive decline, cardiovascular disease, and premature death. Crucially, this approach avoids the extremes of trendy or restrictive diets, focusing instead on variety, flavour, and long-term sustainability. These benefits extend beyond physical health. Balanced diets are also linked with improved mood, better sleep quality, and reduced risk of depression - all of which become increasingly important with age.
Hydration is another simple but frequently overlooked factor. As we age, our sense of thirst diminishes, increasing the risk of dehydration, which can exacerbate fatigue, impair concentration and even raise the risk of falls. Drinking regularly throughout the day - even before feeling thirsty - is especially important for older adults, as is consuming fluids from both drinks and hydrating foods like fruits and vegetables. Are you properly hydrated? Learn more here.
Ultimately, while 'anti-ageing diets' make headlines, the most effective approach is both practical and personal: avoid excess, prioritise whole and minimally processed foods, meet your protein needs and stay well hydrated. Fad diets and costly supplements rarely outperform this kind of common-sense nutrition - and the review makes it clear that good dietary choices, like physical activity, are proven tools we can act on right now.
Sleep, Social Connection and Mental Wellbeing
Ageing doesn’t happen in a vacuum. The review also draws attention to lifestyle factors like sleep quality and social health, both of which can significantly influence healthspan.
Inadequate or excessive sleep is linked to increased mortality, while poor sleep also impairs cognitive function, immunity, and mood. Aiming for 7 to 8 hours of quality sleep per night is ideal. Physical activity can improve sleep quality, and in turn, better sleep supports exercise recovery and mental clarity. Enjoy our sleep focused articles here.
Equally vital is social connection. Loneliness and chronic stress increase mortality risk and contribute to inflammation and poor health. Maintaining friendships, engaging in meaningful activities, and nurturing a sense of purpose are all associated with longer and healthier lives. These psychosocial factors aren’t just nice to have - they're crucial components of ageing well.
Final Thoughts
Rather than waiting for a miracle molecule, Furrer and Handschin urge a return to basics. While the race to decode the molecular mechanics of ageing continues, the best tools to assess and influence our biological age are already within reach: VO₂max, grip strength, gait speed and activity levels. These markers not only predict how we age, but also guide us toward effective actions to age well.
We could also argue that diet could be similarly assessed: meeting daily fibre intake recommendations, aiming for 30 different plants per week, eating sufficient but not excess protein. And, with these foundations properly in place, further evidence based strategies and tactics can be pursued to add value - rather than to avoid building the lifestyle based foundations.
In the end, ageing well isn’t about chasing youth - it’s about preserving function. With the right lifestyle choices and simple, reliable tests, we can track our progress and invest in the only longevity strategy that works today: moving more, eating well, sleeping deeply and living with purpose.
Changing your health for the better is about progress, not perfection, and even small changes can have a powerful and positive effect on health. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.
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Stay Healthy,
Alastair
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Related Studies
Biomarkers of aging: from molecules and surrogates to physiology and function Regula Furrer and Christoph Handschin, Physiological Reviews 2025105:3,1609-1694
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