Unquantifiable Biomarkers of Elite Health
11 functional signals for stress resilience, metabolic flexibility, & circadian alignment
You can’t spreadsheet your way to a life well lived.
Some of the most predictive markers of long-term health resist quantification entirely. They exist in daily patterns, subjective experiences, & functional capacities that no device can capture — a human feature, not a bug.
This isn’t an argument against leveraging data. But the longevity space continues to solely chase quantifiable metrics with little reverence to the unquantifiable signals of health. We need both.
If elite health has a phenotype, this is what it looks like in practice.
Here are the 11 subtle signs you’re in an elite health status.
Sign #1: High Sleep Pressure & Low Anxiety ~9 PM
Feeling genuinely tired 1-2 hours before bed is one of the most reliable indicators of circadian synchronization you can track without any tech.
The Science of Sleep Pressure
Your sleep drive operates through two complementary systems1: homeostatic sleep pressure (Process S) & circadian timing (Process C). Process S builds throughout the day as adenosine accumulates in your brain. Process C syncs to your light environment creating predictable daily rhythms.
Around 9 PM, natural sleep drive peaks2. As the day progresses, adenosine builds up and binds to adenosine receptors (A1 & A2A). If adenosine sounds familiar, that’s because caffeine functions by blocking these receptors to promote wakefulness. Accumulated adenosine suppresses wake-promoting neurons (i.e. orexin, histamine) while activating sleep-promoting pathways & melatonin release.
The Cortisol Connection
Evening calmness is equally telling. Healthy cortisol levels follow a natural daily pattern: peaks 2-3 hrs after waking, drops rapidly around midday until ~8 PM before eventually hitting its trough ~9 PM.
Low stress & anxiety in the evening signal this rhythm is intact.
What Sets the Timer?
Low-angle sunlight rich in red & infrared wavelengths. Each sunrise flips an hourglass — setting a biological timer determining when you’ll feel sleepy that evening. Bright midday light & sunset exposure reinforce the signal.
Final note here: If you want to understand just how critical circadian alignment is for metabolic, immune, & cognitive health in particular — invert to see the ramifications of chronic circadian misalignment3. (Abridged Version: Less than ideal.)
Sign #2: Daily Bowel Movements
Until recently, “normal” bowel frequency ranged from multiple times daily to a few times per month. We now understand how abnormal infrequent elimination actually is.
The Gut-Brain Connection
Ma et al. (2023)4 analyzed 112,000 subjects and found bowel movements fewer than 4x/week correlated with ~3 years of accelerated cognitive aging & 73% worse overall cognitive function.
The implications extend beyond the brain.
Mortality Risk
A review by Peng et al. (2022)5 of nearly 15,000 subjects showed pooping fewer than 7x/week increased all-cause mortality risk by 43% compared to daily movements. Those having bowel movements just once weekly faced the highest risk.
Frequency alone doesn’t tell the complete story. Compared to 7x/week, those pooping 4x/week with soft stools showed:
1.78x higher all-cause mortality
Relationship between stool frequency & all-cause mortality 2.27x higher cardiovascular mortality
Relationship between stool frequency & CVD mortality 2.42x higher cancer mortality
What Healthy Elimination Produces
Johnson-Martinez et al. (2024)6 examined 1,400 healthy adults. Those pooping 1-3x daily had significantly higher levels of beneficial short-chain fatty acids like butyrate and greater proportions of protective bacteria.
Conversely, bowel movements fewer than 3x/week correlated with elevated blood toxin levels.
The Mechanism
Let’s provide a simple breakdown on this:
Infrequent bowel movements
Stool remains in the colon longer
Gut bacteria switch from fiber as main fuel to fermenting protein
Without fiber - our gut microbiome starts producing harmful metabolites like phenylacetylglutamine (linked to CVD) & indoxyl-sulfate (linked to kidney damage)
Toxins enter bloodstream
Negative long-term outcomes downstream = more anxiety + more visceral fat + more systemic inflammation + acceleration of artery hardening + more neurodegeneration
Sign #3: Effortless 36-Hour Fast
Fasting capacity functions as a stress test for metabolic health. Specifically, your ability to switch fuel sources efficiently.
The Metabolic Switch
This refers to your body’s capacity to transition seamlessly from burning glucose to oxidizing fatty acids & ketone bodies. The ease with which you complete a 36-hr fast reveals how well this metabolic switch operates.
Insulin Sensitivity Under Stress
Metabolically healthy individuals demonstrate superior insulin sensitivity in adipose tissue. During fasting, insulin receptor binding enhances and overall insulin sensitivity increases 3-4x7.
The idea of becoming more insulin sensitive seems paradoxical while fasting but it demonstrates tissue-level hormone responsiveness despite energy restriction. Your cells remain metabolically flexible under stress (applies for HIIT too!).
Preferential Fat Mobilization
Fat mobilization quality matters as much as quantity. During extended fasting, optimal metabolic health shows up as preferential mobilization of visceral fat stores8.
Not only is it one of the most powerful tools at our disposal to improve leptin & insulin sensitivity. But a 36-hr fast will also make a few eggs & avocado taste like a Michelin star meal.
