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Hair Cortisol Test for Weight Management
Eating well and exercising, but the weight — especially around your middle — won't budge? Chronically elevated cortisol directly drives fat storage, particularly abdominal fat.
A blood test taken on a calm morning might show cortisol within normal range. But if it's been elevated for months — which is what happens under chronic stress — the damage to your metabolism is already underway. Hair testing shows you the real picture.
No blood. No needles.
Quick, easy at-home collection
Free UK postage
Single sample — no repeats needed
Clinically proven with expert support
About this test
Sample method: Hair | Measurement window: 3 months
Cortigenix's Cortisol Over Time (COT) test measures your average cortisol levels over three months — giving you a stable, meaningful reading that isn't thrown off by what happened the morning you took the test.
Cortisol promotes fat storage by stimulating appetite (particularly for high-calorie foods), promoting insulin resistance, and triggering fat deposition around the abdomen — the so-called 'cortisol belly'. These effects are cumulative: it's sustained elevated cortisol over weeks and months that drives the pattern, not occasional spikes.
If your weight gain is driven by cortisol rather than simply calories in vs out, understanding that changes what you should do about it. Reducing cortisol through better sleep, stress management, and targeted interventions can have a more meaningful effect on your weight than further dietary restriction alone.
Signs cortisol may be affecting your weight
High cortisol can cause a distinctive pattern of symptoms alongside weight changes:
- Stubborn abdominal fat that doesn't respond to diet or exercise
- Weight gain concentrated on the trunk with relatively slim limbs
- Puffy or rounded face
- Persistent fatigue and low energy
- Sugar and carbohydrate cravings
- Brain fog
- Difficulty sleeping or poor sleep quality
- Low mood or anxiety
- Recurrent infections
- Skin problems
- Headaches
- Muscle weakness
Who should take this test?
- You're experiencing unexplained weight gain, particularly around your abdomen
- Diet and exercise aren't producing the results you'd expect
- You've been under sustained stress and want to understand its metabolic impact
- You want to know whether cortisol is a factor before pursuing further interventions
- You have signs of metabolic disruption (blood sugar issues, energy crashes, constant cravings)
Why hair testing gives a clearer picture
Blood, saliva and urine tests capture cortisol at a single moment. But cortisol fluctuates constantly — by the hour and by the day — meaning a result on a calm morning can look completely different to one taken during a stressful week. A single snapshot can lead to results that are misleading or missed altogether.
Hair cortisol testing works differently. As hair grows (~1cm per month), cortisol from your bloodstream is incorporated into the hair shaft. Analysing the section closest to the scalp gives a reliable, averaged picture of cortisol exposure over the past three months — unaffected by whether you had a bad night before the test, or exercised that morning.
It's the same principle as an HbA1c test for blood sugar: one measurement that reflects sustained exposure over time, not just today.
Hair vs other cortisol tests
Other cortisol tests only measure where your cortisol sits at a single moment. But cortisol changes minute by minute — which is why a one-off blood test can miss the full picture. Hair cortisol testing works like an HbA1c for blood sugar: it gives you a reliable average over three months, not just a snapshot of today.
| Feature | Hair test Cortigenix | Blood test | Saliva test | Urine test |
|---|---|---|---|---|
| Measures cortisol over 3 months | ✓ | ✗ | ✗ | ✗ |
| Single sample — no repeat testing needed | ✓ | ✗ | ✗ | ✗ |
| Unaffected by acute stress on test day | ✓ | ✗ | ✗ | ✗ |
| Detects chronic (long-term) cortisol patterns | ✓ | ✗ | ✗ | ✗ |
| No needles or clinic visit required | ✓ | ✗ | ✓ | ✓ |
| Suitable for at-home self-collection | ✓ | ✗ | ✓ | ✓ |
| Results unaffected by time of day | ✓ | ✗ | ✗ | ✗ |
| Validated by peer-reviewed research | ✓ | ✓ | ✓ | ✓ |
| Useful for diagnosing adrenal conditions | ✓ | ✓ | ✓ | ✗ |
I've battled weight gain for years, but nothing seemed to work. Thanks to Cortigenix, I discovered my cortisol levels were through the roof, contributing to my belly fat. With targeted lifestyle changes, I'm finally seeing results and feeling more confident than ever.
C Sherriff
Finally, a test that targets the root cause of cortisol belly directly. Unlike other cortisol tests which left me confused, Cortigenix's hair test offers a precise measurement over time, allowing for interventions that actually work. Results came quick. Highly recommend.
E Clarke
How it works
No clinic visit. No needles. Everything by post, all from home.
Step 1
Order your test kit
Step 2
Take a small hair sample at home
Step 3
Post your sample using the prepaid envelope
Step 4
Receive results in your secure portal within 10 days
Sample: A small hair sample from the back of your head — minimum 1cm in length, about 8–10 strands thick. Full instructions included in your kit.
Still have questions?
What is cortisol?
Cortisol is a hormone often called the 'stress hormone' because of its role in helping the body respond to stress. It regulates a wide range of functions: immune response, metabolism, reproductive health, blood pressure, and brain function. Every cell in the body has cortisol receptors, which is why prolonged imbalance — whether too high or too low — can affect so many aspects of your health.
Why measure cortisol over 3 months rather than with a single blood test?
Cortisol fluctuates constantly — it varies by the hour and can spike significantly on a stressful day. A single blood, saliva or urine test only captures a snapshot of one moment, which means a 'high' or 'low' result could simply reflect the circumstances of that morning.
Measuring cortisol in hair provides a reliable average over the past 3 months, in the same way an HbA1c test measures average blood sugar over 3 months rather than a single glucose reading. This makes it far more useful for assessing chronic stress, adrenal health, and long-term cortisol patterns.
Why does this test use hair rather than blood, saliva or urine?
Hair is a stable, long-term record of cortisol exposure. As hair grows (roughly 1cm per month), cortisol from the bloodstream becomes incorporated into the hair shaft. Analysing the section closest to the scalp gives a precise, averaged view of cortisol levels over the preceding three months.
Blood, saliva and urine tests are affected by acute stress, time of day, exercise, and medication taken before the test. Hair cortisol is not — making it a more objective and reproducible measure of your true long-term cortisol status.
What is the science behind Cortigenix's test?
Hair cortisol testing is backed by decades of peer-reviewed research and is used by scientists at institutions including the University of Oxford, King's College London, Harvard University, and the University of Auckland. Our test has been independently validated using data from thousands of participants. Research partners include the University of Nottingham, University of Auckland, and King's College London.
Is your test available worldwide?
Yes. We ship to over 170 countries. UK orders include free postage. International shipping rates are calculated at checkout.
How much hair do I need to provide?
You need a small sample from your head — a minimum of 1cm in length and approximately 8–10 strands thick (around 2–3mm). Full instructions are included in your kit.
Where should I take my sample from?
We recommend taking your sample from the back of your head, near the cranial bone (the bump you can feel at the base of your skull). This area tends to give the cleanest, most consistent results and the sample is not visible once taken.
Will hair dye or treatments affect my results?
No. All hair samples are thoroughly washed before analysis to remove external contaminants, including dyes, bleach, conditioner, and styling products. Your results will not be affected.
How are my results delivered?
Results are delivered to your secure personal dashboard within 10 working days of your sample arriving at our laboratory. You'll receive an email notification when they're ready. If your results are outside the normal range, one of our cortisol experts will be available to discuss next steps.