Stress Leaves Clues: Biomarkers, Health Impact, and Effective Interventions

We often think of stress as a feeling—but your body treats it as a full-scale event.
And over time, chronic stress leaves measurable fingerprints throughout the body.

A systematic review of 37 studies spanning 40 years of research identified the most reliable biomarkers—physiological signals—that rise or fall when stress becomes chronic. The findings give us a clearer picture of how stress affects long-term health and how lifestyle interventions, including exercise, fit into the prevention puzzle.

Key Findings From the Study

The review identified several measurable biomarkers linked to chronic stress across the HPA axis, immune system, metabolic health, and the autonomic nervous system. Here are the most relevant takeaways:

1. Cortisol (Especially Hair Cortisol) Is a Strong Long-Term Stress Marker

• 9 studies supported hair cortisol as one of the most reliable long-term stress indicators.

• Hair cortisol reflects weeks to months of stress exposure—not just a stressful morning.

2. Chronic Stress Alters Brain and Hormonal Signaling

• Low levels of BDNF (brain-derived neurotrophic factor) were consistently found in people experiencing chronic stress.

• Some studies showed changes in ACTH, a hormone involved in the stress response.

3. Stress Has Metabolic Consequences

Chronic stress can elevate:

• Glucose

• HbA1c

• Triglycerides

• Cholesterol

These changes may help explain why long-term stress increases risk for:

• Type 2 diabetes

• Cardiovascular disease

• Weight gain and abdominal fat storage

4. Stress Drives Systemic Inflammation

Studies found higher levels of:

• C-reactive protein (CRP)

• Interleukin-6 (IL-6)

• Interleukin-8 (IL-8)

These immune markers stay elevated even after the stressor passes—one reason chronic stress accelerates aging and lowers immunity.

Why This Matters for Everyday Life

Chronic stress isn’t “all in your head.”
It shows up biologically—and these changes influence how you feel, how you heal, and how you age.

What this means for you:

• Stress can affect your metabolism.
  • That stubborn weight gain during stressful months? The research backs it up.
• Stress impacts your immune system.
  • Higher IL-6 and CRP reflect an inflammatory state that affects recovery, sleep, and sickness.
• Stress affects your brain.
  • Lower BDNF is linked to brain fog, low mood, and reduced learning capacity.
• Stress management should be as routine as exercise.
  • Because chronic stress quietly shapes health outcomes as much as diet, sleep, and strength training.

What FITNESS SF Is Here to Help With

At FITNESS SF, we think about health across the entire lifespan, including how stress affects physical and mental well-being.

We design our spaces and programs to support stress-resilient living:

Movement that lowers cortisol naturally

• Regular exercise is one of the only interventions scientifically proven to reduce chronic cortisol.

Amenities that promote recovery

• Stretching areas, turf space, dedicated quiet corners, and restorative class options create a safe environment for your daily dose of self-care.

Options for every nervous system

Whether your stress response ramps you up (fight-or-flight) or shuts you down (freeze), we offer movement solutions:

• Strength training

• Yoga

• Low-impact cardio

• Functional training

• Team support from trainers who understand behavioral health

You don’t need biomarkers to tell you when you’re overwhelmed—but it’s encouraging to know that your workout (and your "work-in," which is a recovery-focused workout) is one of the most powerful tools you have to keep your stress physiology in balance.