As you age, certain body functions and processes shift. These physiological changes of aging affect multiple systems that impact cognition, cardiovascular health, muscle strength, bone density, weight status, sex hormones, and skin health. Many aging-related changes are involuntary. However, lifestyle modifications—such as sleep, stress, nutrition, and physical activity—can mitigate the effects of aging, promoting longevity and a greater quality of life.
Let’s break down what aging is, how it relates to longevity and the physiological changes that relate to each body system.
What is aging?
Aging is the decline in function resulting from the accumulation of cellular damage.  There is no single explanation for aging. Rather, aging is linked to changes in biological, physiological, environmental, psychological, behavioral, and social processes. Research continues to evolve on how these factors affect age-related chronic diseases. Genetics influence longevity; about 25% of the variation in longevity can be attributed to genetics. But, environmental, social, and lifestyle factors may play a larger role in a longer lifespan and healthspan. [1,2,3]
Aging is not always linear or consistent. It affects all body systems—as people age, they are more likely to experience several conditions simultaneously. By identifying certain aging processes to target with lifestyle modifications, researchers hope to slow the start and progression of diseases and instead establish a path towards a longer lifespan and greater healthspan. 
What is the difference between aging and longevity?
Longevity is the length of the lifespan (the time a person lives) regardless of internal physiological changes associated with aging.  So extending longevity means slowing or prolonging the aging process.
What are the physiological changes of aging?
The physiological changes of aging are characterized by an alteration—usually a decline—in organ function, with these changes accumulating over time. Some aspects of aging are harmless to overall health, like the graying of hair. Other aspects can significantly impact functional abilities and quality of life. The effects of some age-related changes, such as decreases in hormone levels, are not isolated to one organ system. Instead, the consequences of low hormone levels, cognitive impairment, cardiovascular irregularity, or muscle and bone loss are compounded and can propel that progressive decline of health. [1,2,5]
What happens to the cardiovascular system when you age?
Aging can affect the heart health and blood vessels. Research shows that low-density lipoprotein tends to creep up with age. High levels of LDL cholesterol—especially when there’s inflammation present—creates plaques or deposits in arteries, increasing arterial stiffness and hardening. This in turn restricts how much blood can pass through an artery, which increases the likelihood of having high blood pressure and heart disease. 
How to promote longevity?
- A healthy diet: The Mediterranean diet is inversely associated with cardiovascular mortality. Furthermore, the Mediterranean diet may also reduce the effects of other factors (inflammation, oxidative stress, and endothelial dysfunction) on the risk of cardiovascular disease. 
- Coffee: Data suggest moderate coffee intake (2-3 cups per day) may be affiliated with reduced all-cause and cardiovascular mortality. [7,8]
- Moderate-intensity physical activity: Not only does physical activity attenuate the effects of hypertension, hyperglycemia, and dyslipidemia, but it also reduces inflammation and oxidative stress and improves endothelial function. 
What happens to bone health as you age?
Bones are constantly remodeling. During this process, old bones are removed by osteoclasts (bone-degrading cells) and replaced with new bones by osteoblasts (bone-forming cells). 
During childhood and times of growth, the bone-building phase is the dominant phase. But with age, osteoclasts become more prominent and initiate bone breakdown. This causes bones to lose density and become weaker. And the risk of osteoporosis—a bone disease characterized by a decline in bone density and quality associated with aging—and fractures increases. [9,10]
How to promote longevity?
Lifestyle factors, such as diet and exercise, can significantly influence the risk of osteoporosis.
- Physical activity: Exercise is important for improving and maintaining bone mass throughout the lifespan. In particular, weight-bearing exercises preserve bone mass and increase bone strength. Physical activity in older adulthood helps prevent injurious falls and benefits physical function, quality of life, and pain in people at risk of or with osteoporosis. [11,12,13]
- Maintain optimal vitamin D and calcium levels: Include foods rich in vitamin D (like fatty fish, mushrooms, and fortified dairy) and calcium (like dairy or dairy alternatives) to help you maintain optimal blood levels of these nutrients. It can be challenging to meet the recommended daily amount of these nutrients through diet alone, and a blood test can reveal if supplementation would be beneficial. [11,13]
What happens to your body composition and metabolic health as you age?
Body composition refers to the percentage of fat or lean-body mass (that consists of muscle, bone, and water mass). Aging processes promote the breakdown of lean body mass and favor the accumulation of fat mass.  One reason for this shift in body composition is attributed to age-associated decreases in sex hormones—testosterone in males and estrogen in females.  In females, estrogen levels fall drastically after menopause. In males, testosterone levels decrease about 1%-2% each year after age 40 (although low testosterone levels can occur at any age).  Both of these hormones are involved in weight regulation and metabolism, and low levels are associated with weight gain typically in the midsection and abdomen.
Body composition and the accumulation of excess weight also impact metabolic health and blood sugar control. Your metabolism determines how many calories you need a day to maintain bodily functions (like breathing and digesting food) and any physical movement. Muscle has a higher metabolic rate than fat, meaning it requires more calories to carry out its essential functions. Decreases in lead body mass as you age means you need to take in less calories than previously to maintain weight.  Not doing so could lead to weight gain.
How to promote longevity?
- Get regular exercise: Physical activity helps maintain and improve body composition. 
- Consider modest calorie restriction: If calories are currently being consumed in excess, consider a modest calorie restriction. Eating a nutrient-dense diet of fruits, vegetables, whole grains and legumes helps ensure you’re meeting your daily nutrient needs while not consuming excess calories. Calorie restriction that maintains adequate nutrient intake may improve cholesterol and blood sugar. And research shows that calorie restriction of just 10% can improve chronic disease risk factors and contribute to longevity. 
- Sip on green tea: Green tea can be beneficial for maintaining a healthy body composition, and the antioxidants in the beverage are also associated with longevity. 
What happens to muscles as you age?
Loss of muscle mass and strength, known as sarcopenia, often accompanies aging. Research into the cause of sarcopenia is constantly evolving, and scientists believe its onset is likely related to neurological declines, hormone alterations (like those described above), nutrition, and/or exercise. Together, these age-related imbalances in normal cell processes contribute to sarcopenia, as signals for cell breakdown dominate signals for cell growth. [21,22]
Sarcopenia is associated with mortality. Lower muscle mass and strength lead to imbalances and frailty, which increases the risk of falls. 
How to promote longevity?
- Eat adequate amounts of protein: Sufficient protein intake is required to maintain muscle mass. The current recommendation for protein intake in older adults is 1.0-1.3 per kilogram of body weight (g/kg). [24,25] For reference, those recommendations indicate that someone weighing 150 pounds should eat between 68 and 82 grams of protein a day.
- Stay physically active: The best way to minimize sarcopenia is to keep the muscles active—a combination of aerobic exercise, resistance training, and balance exercises can help maintain muscle mass and strength. 
- Consider leucine supplementation: Leucine is an essential amino acid and supplementation may increase muscle mass in older adults. But, supplementation alone does not seem to affect muscle strength or physical function. 
- Consider creatine supplementation: In addition to exercise, creatine supplementation may improve muscle mass and strength. 
What happens to cognition as you age?
The brain changes as we age. Shrinking neurons and changes to how those neurons communicate affect memory, recall abilities, problem-solving and multitasking capabilities, and attention span. [27,28]
How to promote longevity?
- Add fish to your diet: Eating just one serving per week of fish can lower the risk of cognitive impairment, particularly dementia and Alzheimer’s disease. 
- Play brain games: The brain holds onto some plasticity with age. So, brain-training games may benefit cognitive function in older adults. Specifically, cognitive mobile games may improve processing speeds and the ability to complete complex tasks. [30,31]
- Sulforaphane benefits cognition: Sulforaphane, a bioactive compound found in broccoli and cauliflower, improves processing speed and mood. 
What happens to sex hormones as you age?
A decline in sex hormones accompanies aging and contributes to a proinflammatory state.
Dehydroepiandrosterone-sulfate (DHEAS), a precursor for sex hormones, helps maintain energy, muscle and bone health, and sexual function. Low levels of DHEAS in women are associated with stress and poor sleep. Moreover, DHEAS decreases with age. Similarly, testosterone levels in males and estrogen levels in females decrease with age, affecting sex drive, sexual function, and bone and muscle health. [33-35]
How to promote longevity?
- Reduce stress: Supplementing with the herb ashwagandha can reduce stress and increase testosterone levels in males. However, research is inconsistent on the effect of Ashwagandha on DHEAS levels. In one randomized control trial of overweight males, supplementing with Ashwagandha increased testosterone levels. Another randomized control trial of both males and females found that Ashwagandha decreased DHEAS levels in males and females and increased testosterone levels in only males. [36,37]
- Ensure sufficient sleep: Poor sleep quality increases the risk of low testosterone and sexual dysfunction. Changes to sleep duration and quality alter DHEAS; higher levels of DHEAS may be associated with better sleep quality. [35,38,39]
What happens to skin health as you age?
The skin often provides the first visible signs of aging. Some people may notice wrinkles, pigmented spots, and loss of plumpness starting in their 20s or 30s. Skin aging is driven by multiple factors including collagen decreases (a protein in connective tissue that supports skin elasticity), alterations in facial fat and muscle distribution, genetics, and hormonal shifts. And environmental and lifestyle factors—such as UV light and smoking—can accelerate aging and leave noticeably visible signs of age earlier. 
How to promote youthful skin?
- Wear sunscreen: Daily use of a broad-spectrum and photostable (greater efficacy with sun exposure) sunscreen with at least 30 SPF may reverse existing signs of photodamage and prevent additional sun damage to the skin. 
- Consider a vitamin C serum: Vitamin C’s effect on skin health is twofold: it plays a role in collagen synthesis to maintain skin elasticity and acts as an antioxidant to protect against damage from UV radiation. 
InsideTracker can support your journey of extending your healthspan and living a longer healthier life
While extending your lifespan can add years to your life, extending your healthspan helps you enjoy and stay active in those later years. InsideTracker is designed to help you live healthier longer by providing you with personal health analysis and a data-driven wellness guide. No matter what your age is now, it’s never too early or too late to invest in yourself. Tracking your biological age with InsideTracker's InnerAge 2.0 provides unique insights into how your body is aging, recommendations to improve on those markers of aging, and motivation for lowering or maintaining a lower biological age than chronological age.
A summary of the physiological changes of aging
Some aging processes are (eventually) inevitable. But, implementing small lifestyle changes to nutrition and exercise routines can prevent the early onset of aging and associated chronic diseases and extend your healthspan—the period of your life living in good health.
- Aim for at least 150 minutes of moderate-intensity aerobic exercise and two sessions of resistance training every week
- Play brain games to maintain and improve cognition.
- Aim to increase your protein intake to at least 1 g/kg of body weight per day.
- Wear a broad-spectrum sunscreen with at least 30 SPF