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What is Biological Age?

You’re 45 years old, but is your body? That’s the question biological age tries to answer.

Your chronological age is simply how many years you’ve been alive. Your biological age looks deeper, examining patterns across your blood biomarkers to estimate whether your body more closely resembles someone younger, older, or right around your actual age.

Think of it as a health fingerprint translated into a single, trackable number.

How to Interpret Your Result

  • Lower biological age: Your overall biomarker pattern looks more similar to people who are chronologically younger.
  • Higher biological age: Your overall biomarker pattern looks more similar to people who are chronologically older. This can be a useful prompt to focus on areas that may be holding your health back.
  • Similar to your chronological age: Your biomarker pattern is broadly similar to others in your age range, which is common.

A helpful way to think about this: biological age is a summary signal, not a diagnosis. It reflects the combined “shape” of your biomarker profile, not any single result.

Why It Matters

Biological age can help you:

  • See the bigger picture across multiple body systems (metabolic, cardiovascular, inflammation, hormones, and more).
  • Track trends over time, especially when you test consistently.
  • Identify areas to prioritize when paired with your biomarker insights and action plan.

Here’s what makes biological age especially useful: because biomarkers respond to lifestyle, sleep, stress, nutrition, and medical care, your biological age can change. Unlike your chronological age, this number isn’t fixed.

How Is Biological Age Calculated?

There is no single lab test that directly measures “true” biological age, so models like ours learn how biomarker patterns typically vary with age across large populations, then compare your results to those patterns.

At a high level, our approach works like this:

  • Training data: We trained our model using a combination of large public health datasets and internal data.
  • How your score is generated: When you get results, the model compares your biomarker pattern to the patterns it learned and estimates the age your profile most closely resembles.

How Accurate Is It?

Biological age is an estimate. It is designed to be directionally meaningful and consistent over time, especially when you retest under similar conditions.

Short-term factors (illness, major sleep disruption, inflammation, medication changes, recent supplementation, training load, etc.) can temporarily shift biomarkers and influence the score. Some biomarkers can move in ways that are “health-positive” but still correlate with age trends in population data (for example, supplementation effects), which can sometimes affect the estimate.

Why Your Biological Age May Change Over Time

It’s normal for biological age to shift between tests because your biomarkers change with lifestyle, recovery, stress, and health status. Normal biological variation and lab variation exist, and the model may be updated over time as we expand training data and improve performance.

For interpretation, it’s best to focus on your trend over multiple tests, which biomarkers are driving the change, and whether changes match how you feel.

Biological Age vs. Heart & Metabolic Age

If you’ve also completed a Heart & Metabolic panel, you’ll see a second age estimate. Heart & Metabolic Age is a structured score translated into an age-like number based on the SiPhox Heart and Metabolic phenotype.

Biological Age uses a broader set of biomarkers and a machine learning approach trained on population patterns across age and sex. It is intended to reflect a more general “whole-body” biomarker aging signal rather than one specific domain.

Both are useful. Heart & Metabolic Age tells you how your cardiovascular system is holding up. Biological Age gives you a wider lens on overall aging. If you have access to both, consider them complementary views of your health.

Important Notes

  • Biological age is not a medical diagnosis and should not be used alone to diagnose or treat any condition.
  • It does not capture every factor that influences aging (genetics, imaging findings, fitness, body composition, sleep quality, medical history, and more).