Calculating Your Biological Age, or: The Number That Really Matters

Your date of birth might be fixed—but how old your body truly is tells a completely different story. Your biological age reflects the health of your cells, organs, and metabolism. The best part? You have the power to influence it.

What Is Biological Age?

Let’s say you’re 35 years old. That means you’ve travelled around the sun 35 times. But how old are you—your body, your mind—really?

That depends on how fast your body is actually ageing. Biological age describes the true biochemical state of your cells, tissues, and organs. For many people, their biological age roughly matches their chronological age, meaning they have an average life expectancy. But for others, their biological age may be significantly higher or lower than their actual years—a sign of either below- or above-average health and longevity.

Grey hair and wrinkles are visible signs of ageing. But the real transformation happens at the cellular level. Over time, small damages accumulate, affecting the ability of cells to regenerate and function properly. When these “aged” cells dominate tissues and organs, we start to see the effects of ageing: muscle loss, frailty, and increased risk of chronic disease.

While genetics play a role in how quickly our internal clock ticks, lifestyle and nutrition have a profound impact on the ageing process.

How to Calculate Your Biological Age: Methods and Accuracy

A quick search online will bring up plenty of free biological age calculators that promise an instant answer. But be cautious: the fewer data points used, the less reliable the result.

Simple calculators rely on a formula using basic information like age, BMI, blood pressure, and cholesterol levels to produce a rough estimate of biological age.

However, more advanced methods now offer highly precise calculations without relying on a fixed formula. Instead, machine learning models process extensive health data sets, trained on large-scale medical studies. These models analyse multiple biomarkers to determine biological age, including:

• Blood markers: Inflammation levels, blood sugar, and cholesterol reflect internal health and metabolic function.
• Physical performance indicators: Lung capacity, grip strength, and walking speed provide insight into overall fitness.
• Epigenetic testing: Advanced techniques assess chemical modifications in DNA that change with diet, activity, and lifestyle.

The more detailed the data, the more accurate the biological age calculation.

Biological Age vs. Metabolic Age—What’s the Difference?

You may have also come across the term metabolic age. Is it the same thing? Not quite. While biological age reflects overall cellular health, metabolic age is a fitness-focused concept.

Metabolic age is based on basal metabolic rate (BMR)—the amount of energy your body burns at rest. This number is compared to the average BMR of people in your age group.

As you age, your metabolism naturally slows, largely due to muscle loss. Muscle tissue burns energy even when inactive, meaning a decline in muscle mass can lower your daily calorie burn and make weight management more difficult.

While biological age gives a comprehensive picture of health, metabolic age focuses more on energy efficiency and fitness levels. Though they measure different aspects of ageing, the two are often closely related, as fitness and overall health go hand in hand.

How to Keep Your Biological Age Low

Even though you can’t stop time, you can influence how your body ages. Here’s how:

• Move your body daily: Not just through workouts, but by being more active throughout the day. Even small changes like taking the stairs instead of the lift can make a difference.
• Prioritise a nutrient-rich diet: A diet rich in whole foods, healthy fats, and protein supports cellular function and regeneration.
• Reduce lifestyle stressors: Smoking, excessive alcohol consumption, and chronic stress accelerate cellular ageing.
• Optimise your nutrient intake: Vitamins and minerals play a crucial role in supporting overall health and longevity.