Ageing is not simply a matter of watching the years tick by on the calendar. Beneath the surface, profound changes occur within the body—some visible, many hidden. Among the most significant but least understood of these changes is the gradual loss of muscle mass and the insidious accumulation of visceral fat.

Visceral fat, the deep-lying fat that wraps itself around vital organs such as the heart, liver, and kidneys, has long been linked to a host of health concerns.

Now, emerging research presented at the Radiological Society of North America’s annual meeting offers new insights into how the balance between muscle and visceral fat may be intimately connected with brain health.

Scientists have revealed an intriguing relationship: individuals with greater muscle mass and a lower ratio of visceral fat to muscle tend to possess brains that appear biologically younger than their actual age.

This connection is no minor detail. According to experts, a younger-appearing brain is less likely to succumb to Alzheimer’s disease and other forms of dementia, conditions for which advancing age is the most powerful risk factor.

As specialists in radiology and neurology explain, chronological age—the number of years since birth—may not align neatly with the age of one’s organs or even the brain itself. The apparent age of the brain, measured by advanced imaging techniques and sophisticated algorithms, sometimes tells a different story.

Recent studies have shown that disease processes often cut across organ systems, defying tidy anatomical boundaries.

To explore these links, researchers conducted a comprehensive study involving over 1,100 adults with an average age just past 55. Using whole-body MRI scans, they assessed not only body fat and muscle but also brain structure. An algorithm trained on thousands of healthy adult scans estimated each participant’s “brain age.” The average brain age was slightly higher than participants’ actual ages, but this difference was not statistically significant.

What stood out, though, was the clear trend: higher muscle mass and a lower visceral fat-to-muscle ratio were associated with younger-appearing brains.

Conversely, those with less muscle and proportionally more visceral fat had brains that looked older than they should. Crucially, this pattern did not extend to subcutaneous fat—the layer found just beneath the skin. Only visceral fat seemed to have this potent link with brain ageing.

Why does hidden fat matter so much? Specialists point out that visceral fat is metabolically active. It raises inflammation throughout the body, contributes to insulin resistance and higher cholesterol, and increases the risk of diabetes.

Over time, this persistent inflammatory state appears to damage the brain’s structure and function, providing a plausible mechanism for why excess visceral fat might raise the risk of cognitive decline and dementia.

These findings add weight to mounting criticism of traditional measures like Body Mass Index (BMI). While BMI remains a commonly used metric in clinics and public health campaigns, it offers little insight into body composition.

It cannot distinguish between muscle and fat or indicate whether fat is stored subcutaneously or viscerally. Experts caution that someone with a “healthy” BMI could still harbour dangerous levels of visceral fat—and thus face heightened risks for both heart disease and cognitive decline.

Alternative measures such as waist circumference and waist-to-hip ratio offer a better reflection of visceral fat stores. Health authorities recommend that women keep their waist measurement below 89 cm (35 inches) and men below 102 cm (40 inches).

For waist-to-hip ratio, World Health Organization guidelines set thresholds of 0.85 for women and 0.9 for men. Even so, only advanced imaging like MRI can truly quantify visceral fat.

Fortunately, most people do not need costly scans to start making effective changes. Building muscle and reducing visceral fat can be achieved through simple lifestyle modifications. Physical activity stands out as the single most effective intervention—regardless of age or baseline fitness.

Guidelines from the American College of Sports Medicine recommend that adults engage in muscle-strengthening activities at least twice weekly. These exercises should target all major muscle groups.

A practical approach involves performing 10 to 15 different exercises, each for one to three sets of eight to twelve repetitions. Beginners often find machines helpful for learning proper technique.

Aerobic exercise—such as brisk walking, cycling or swimming—is especially effective at targeting visceral fat. Health authorities suggest aiming for at least 150 minutes of moderate-intensity aerobic activity each week.

Importantly, experts stress that significant benefits occur even with modest efforts. The first few minutes of exercise provide a surprising return on investment in terms of health gains.

For those put off by the thought of gyms or expensive equipment, there is good news: resistance training can be performed using one’s own body weight. Press-ups, squats and lunges are all effective ways to build strength without any special kit.

Muscle does more than support movement; it acts as a powerful endocrine organ, releasing chemical signals during exercise that are thought to benefit brain health directly. This may help explain why regular physical activity consistently lowers risk for cognitive decline, dementia and even Alzheimer’s disease.

The significance of strong muscles extends beyond cognition. Evidence suggests that fitness is one of the strongest predictors of whether people remain independent in later life or require nursing home care. Maintaining muscle mass is crucial for healthy ageing.

Weight loss presents its own challenges. As more people use drugs such as GLP-1 agonists for diabetes or weight management, awareness grows about unintended muscle loss during rapid weight reduction. Regardless of whether weight loss results from medication, surgery or simple calorie restriction, around 30% of lost tissue is lean mass—including precious muscle.

Thus, experts recommend that anyone attempting significant weight loss should incorporate strength training into their routine. Even those not actively trying to lose weight need robust muscles for longevity and quality of life.

Longevity remains a popular goal, but living longer only has value if those extra years are healthy and fulfilling. Maintaining healthy muscle mass alongside minimising visceral fat emerges as an attainable strategy for supporting both body and mind into old age.

The latest research highlights an important truth: what lies beneath our skin matters as much as what we see in the mirror. Ageing gracefully is not out of reach; it requires attention to lifestyle choices that support strong muscles and discourage the accumulation of harmful deep belly fat.

While brain ageing cannot be reversed, its pace can be slowed through regular exercise—building strength and maintaining an active lifestyle are keys to keeping both body and mind resilient against the passage of time.