If you’ve ever thought, “I don’t feel my age,” you might be right. Your actual age (the number of birthdays you’ve celebrated) doesn’t always match what’s happening on the inside. That’s where biological age comes in — it offers a more complete picture of how your body is functioning and how it’s responding to time, lifestyle and overall health.
As part of Felix’s Longevity assessment, you’ll receive your biological age along with your lab results. This post breaks down what that number means, how it’s calculated and why it matters.
What’s the difference between biological age and chronological age?
Your chronological age, or actual age, is simple: it’s how many years you’ve been alive.
Your biological age is different. It looks at how your body is actually functioning, based on key physiological and molecular markers (things like blood sugar, inflammation and liver function). In other words, biological age tells you how “old” your body seems compared to others your age.
- If your biological age is lower than your actual age, it’s a sign you may be aging more slowly.
- If it’s higher, it could mean accelerated aging. It could also mean that you’re at a greater risk for chronic conditions like heart disease or diabetes.
Think of it as the difference between mileage and the year on a used car. Two cars from the same year can have very different wear and tear depending on how they’ve been driven. Your body works the same way.
Biological age: What it means and how to calculate it
Felix uses Levine’s phenotypic age, one of the most widely accepted and scientifically validated using blood only.
Developed by Dr. Morgan Levine and her team in 2018, this method was designed to predict lifespan and overall health more accurately than chronological age alone. The researchers analyzed large health datasets and identified nine key biomarkers that reflect how well the body is functioning. These include markers related to:
- Blood sugar
- Inflammation
- Liver and kidney function
- Immune system performance
- Red and white blood cell counts
The model uses a mathematical formula that combines these biomarkers with your actual age to calculate your biological age—giving you a clearer picture of how your health compares to others your age, and how your body is responding to things like stress, sleep, nutrition and more.
Why does biological age matter?
Biological age is more than just a “fun fact,” it’s a powerful tool for preventative care. It helps you:
- Understand your long-term health risks: A higher biological age can signal increased risk for chronic diseases like diabetes, cardiovascular disease or cognitive decline.
- Measure the impact of lifestyle changes: If your biological age improves over time, it’s a sign your habits are paying off.
- Personalize your health goals: Knowing how your body is aging can help tailor your treatment plans, whether that means medication, diet changes or supplements.
- Stay motivated: Tracking your biological age gives you a tangible, trackable goal.
What affects your biological age?
Several factors play a role in how fast or slow your body ages. Some are within your control — others, not so much.
Lifestyle choices
- Diet (especially fibre, protein and processed food intake)
- Exercise habits
- Sleep quality
- Stress management
- Smoking and alcohol use
Underlying health conditions
- Diabetes
- Cardiovascular disease
- Chronic inflammation
Genetics
- Your family health history can also influence your biological aging rate.
How to use your biological age to make better health decisions
Once you’ve received your biological age, the next step is action. Whether your score came back younger or older than expected, you now have a snapshot of where your health stands and a roadmap for what to improve.
At Felix, your practitioner will walk you through your results and provide a personalized care plan. That may include:
- Nutrition or exercise tweaks
- Supplements to fill in gaps
- Medical treatment for specific conditions (if necessary)
- Lifestyle recommendations
Over time, these small changes can add up to big shifts in your biological age and overall wellbeing.
The bottom line
Biological age gives you insight into how your body is actually doing and is one of the clearest signals we have for understanding longevity.
And now, thanks to Felix’s Longevity assessment, that information is at your fingertips.
Medically reviewed by
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