A biomarker is any measurable signal your body gives off that helps you understand what’s going on inside.
The word itself is a blend of “bio” (life) and “marker” (indicator), meaning it’s a marker of biological activity. As it’s a relatively new word, there’s not long-held consensus on a single definition, though medical experts have been using the word in practice, not always with the same intended meaning.
Researchers Kyle Stimbu and Jorge Tavel define it as:
The term “biomarker”, a portmanteau of “biological marker”, refers to a broad subcategory of medical signs – that is, objective indications of medical state observed from outside the patient – which can be measured accurately and reproducibly. Medical signs stand in contrast to medical symptoms, which are limited to those indications of health or illness perceived by patients themselves.
In practical terms, a biomarker could be your heart rate, blood glucose level, hormone concentration, or even your sleep cycle.
These signals help you and your doctors get a clearer picture of your health, especially in relation to your health history and goals.
Why this matters to you
Biomarkers aren’t just for researchers and labs anymore. Thanks to wearables, apps, and at-home testing kits, many people now use biomarkers to guide personal health decisions.
Checking your heart rate with a smartwatch, measuring blood sugar with a CGM — these are all biomarkers that you can objectively use to evaluate a medical state.
They give context to how you feel, like connecting mood swings with hormonal changes or fatigue with poor sleep, and allow you to take action based on real data instead of just intuition.
What biomarkers tell us
Biomarkers provide information about how your body is functioning. Some are basic and tracked by most annual checkups, like cholesterol and blood pressure. Others are more cutting-edge, like inflammatory cytokines or BDNF (a protein related to brain health).
Together, they help reveal:
How your metabolism is working
Whether you’re recovering well from workouts or illness
If your inflammation levels are high
How well you’re aging biologically
Whether your immune system is active or strained
| Category | Example Biomarkers | What They Indicate |
|---|---|---|
| **Hormonal** | Cortisol, melatonin, testosterone, estrogen | Stress, sleep, reproductive health |
| **Metabolic** | Glucose, insulin, triglycerides | Blood sugar stability, fat processing |
| **Cardiovascular** | Resting heart rate, blood pressure, VO2 max | Heart health, endurance |
| **Inflammatory** | CRP (C-reactive protein), IL-6 | Acute or chronic inflammation |
| **Neurological** | BDNF, serotonin, dopamine | Brain function, mood, mental clarity |
| **Fitness Recovery** | HRV (heart rate variability), body temperature | Stress, readiness to train |
These biomarkers are available through different methods: labs, wearables, at-home kits, or continuous monitoring devices.
How biomarkers are measured
You don’t need to visit a hospital to start measuring your biomarkers anymore. Here’s how people are doing it:
Wearables: Devices like Oura Ring, WHOOP, Fitbit, and Apple Watch can track HRV, temperature, sleep cycles, and resting heart rate.
Lab tests: Standard blood panels ordered by a doctor can reveal cholesterol, glucose, hormone levels, and more.
At-home kits: Companies now offer test kits for biomarkers like vitamin D, cortisol, and inflammatory markers using blood, saliva, or urine.
Continuous monitors: CGMs (continuous glucose monitors) track blood sugar in real time, especially helpful for diabetics, athletes, and biohackers.
Why biomarkers matter for understanding health and longevity
Most health problems don’t happen overnight. Biomarkers allow you to catch trends early before symptoms become crises. Here are a few examples:
A rising fasting glucose level could be the first sign of insulin resistance.
Low HRV might signal chronic stress and poor recovery.
Elevated CRP might indicate low-grade inflammation that could lead to future disease.
By paying attention to these signals, you can adjust your habits before serious problems develop. This is the difference between reactive and proactive health.
Biomarkers are your body’s breadcrumb trail
Biomarkers are like clues your body leaves behind. When you understand them, you stop guessing and start making informed decisions. You begin to spot patterns, what affects your energy, mood, sleep, performance, and respond accordingly.
You don’t need to be a scientist to start using biomarkers. You just need curiosity, the right tools, and a willingness to pay attention. It’s a powerful way to take control of your health, one signal at a time.
Explore biomarkers:
