Notes from building a longevity tracker, in public.
The papers I'm reading. The data I'm staring at. Where the wearable signal is real and where it's noise. What's actually moving people's bio age, and what's marketing.
New posts when I have something worth saying. RSS
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Protein and longevity: the RDA is wrong for healthy aging (here's the actual number)
The 0.8 g/kg/day RDA was set in 1968 against young adults. Forty years of evidence has moved on. The PROT-AGE consensus puts healthy aging at 1.2-1.6 g/kg/day, distributed across 3-4 meals each above the leucine threshold. The biology, the meal-distribution math, why the Longo cancer-mortality finding aged poorly, and why the kidney worry is unfounded in healthy adults. With peer-reviewed citations.
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Alcohol and longevity: what the evidence actually supports (the J-curve is dead)
For 30 years, "1-2 drinks a day is good for you" was treated as established public-health science. The Lancet 2018 Global Burden of Disease analysis buried it. The safest level of alcohol consumption for overall health is zero drinks per week, with a roughly linear dose-response above that. The biology, the J-curve myth, the cancer + HRV + sleep architecture costs, and a harm-reduction framework if you do drink. With peer-reviewed citations.
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What your Apple Watch doesn't tell you about your bio age (and how to fill the gap)
Apple Watch is the highest-fidelity consumer biometric collector ever built. The Health app is a high-quality data viewer. Neither is, or will be, a bio-age model or a daily-protocol coach - that's a deliberate platform choice, not a technical limit. What your Watch already collects, what's missing, and how to fill the gap with a transparent bio-age model on top. With peer-reviewed citations.
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Thier vs InsideTracker: which biological-age tool is right for you?
Two of the most prominent commercial biological-age tools, answering different questions with different data sources at different price points. InsideTracker is a quarterly lab panel + InnerAge score. Thier is a continuous wearable-anchored bio-age model with a transparent coefficient table and a daily protocol layer. Where each excels, where each falls short, and how to pick the right tool for your goal.
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Thier vs Oura: which longevity tracker is right for you?
Oura is a ring-bound sleep + recovery tracker with the strongest consumer sleep-stage model on the market. Thier is a multi-source biological-age tracker across 13 health domains with no required hardware. Where each excels, where each falls short, and why the Oura + Thier combination is the path most serious users land on. With peer-reviewed context.
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Thier vs Whoop: which longevity tracker is right for you?
Whoop is a strap-bound recovery + strain coach built around the daily training-readiness loop. Thier is a multi-source biological-age tracker with a transparent coefficient table and a daily protocol layer, running on whatever wearable you already own. Where each excels, where each falls short, and a clear-headed walk through which to pick for your goal. With peer-reviewed citations.
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Cognitive decline isn't inevitable: the evidence-based playbook for protecting your brain
The Lancet 2024 dementia commission estimated that 14 modifiable risk factors account for around 45% of dementia cases worldwide. The FINGER trial showed a 2-year multi-domain lifestyle intervention preserved cognition in at-risk older adults. The cardiovascular-brain link, the glymphatic clearance window, cognitive reserve, APOE4, and the popular brain-health claims the trials do not support. With peer-reviewed citations.
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Sauna and longevity: what the Finnish cohort data actually shows
The Finnish KIHD cohort followed 2,315 middle-aged men for two decades. 4-7 sauna sessions per week were associated with a 40% lower all-cause mortality, 50% lower fatal CV events, and 66% lower fatal dementia. The biology of heat stress, the dose-response, what the evidence supports, and the caveats. With peer-reviewed citations.
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Strength training vs cardio for longevity: why you need both, in different doses
"Should I run or lift?" is the wrong question. Cardio defends the cardiovascular system, which is the single biggest mortality driver for the next twenty years of your life. Strength training defends muscle mass and bone density, which determine whether you can live independently at eighty. The biology of each, what the cohort data shows, how to fit both into a real week, and what the evidence does not support. With peer-reviewed citations.
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How many steps per day actually move the longevity needle?
Few numbers in modern health are quoted as often, and questioned as rarely, as 10,000 steps a day. It is on every wearable, every workplace wellness program, every walking-meeting argument. It is also, almost entirely, a 1965 Japanese pedometer marketing slogan. The mortality cohorts published since have told a different story: the dose-response flattens earlier than most people think, cadence carries a signal independent of raw count, and the optimal target moves with age. With peer-reviewed citations.
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Sleep stages and longevity: what deep sleep and REM are actually doing for your bio age
A wearable that shows you a four-coloured "sleep stages" chart every morning has done something subtle: it has made invisible biology visible. Each colour band corresponds to a different cellular process - glymphatic clearance, memory consolidation, growth-hormone release, emotional re-coding - and each has a measurably different effect on how your brain and body age. The biology, the dose, and how to read your wearable's data without over-interpreting it. With peer-reviewed citations.
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Zone 2 cardio for longevity: the 'easy' training that actually slows aging
It feels almost too easy to be doing anything. You can hold a full sentence without breathing hard, you do not sweat much, and you finish wondering if you should have pushed harder. That conversational pace - zone 2 - is the most under-trained and over-evidenced endurance intensity in all of preventive medicine. The biology, the dose, how to find your zone without a lab, and what the published evidence actually supports. With peer-reviewed citations.
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The science of HRV: what your heart-rate variability really tells you about recovery, stress, and your bio age
Heart-rate variability is on every modern wearable, but most users have no idea what the number is actually measuring or why it matters for longevity. We walk through the autonomic-nervous-system biology, why a single-day reading is mostly noise, what a healthy trend looks like for your age, and the four levers with the strongest published evidence for actually moving it. With peer-reviewed citations.
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7 things that age you faster than smoking: an evidence-based ranking by years-of-life-expectancy lost
Smoking has been the benchmark "worst thing you can do to yourself" for half a century - a lifelong habit costs about ten years of life. What does not get the same headlines is that several extremely common, extremely tolerated behaviours quietly carry the same or larger hazard. We ranked the seven most-cited ones against the smoking benchmark, using published cohort data - not vibes.
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How accurate is your bio age? A guide to the science behind VO₂ max, RHR, HRV, and what 'biological age' really measures
Every wearable, lab kit, and longevity app now reports a "biological age" number. We walk through the underlying biomarkers - VO₂ max, resting heart rate, heart-rate variability, blood-based epigenetic clocks - what each one is really measuring, how well it predicts what matters, and where the honest uncertainty bands sit. With peer-reviewed citations.
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How to lower your biological age in your 40s: an evidence-ranked playbook
Your forties are the decade biological age can either accelerate past chronological age or quietly fall behind it. The window matters: most age-related disease processes that show up in your sixties have their inflection point in your forties. Eight inputs are doing most of the work, ranked by effect size from published cohort data.
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How to lower your biological age: 7 evidence-backed daily habits
Your chronological age advances at exactly one second per second. Your biological age does not. Here are the seven daily habits with the strongest published evidence for moving the gap in your favour - what each one does, how big the effect is, and how to actually fit them into a normal life.
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VO₂ max and longevity: why this single number predicts how long you'll live well
VO₂ max - the maximum amount of oxygen your body can use during hard exercise - is one of the most predictive numbers in all of preventive medicine. It correlates more tightly with all-cause mortality than smoking status, blood pressure, or cholesterol. Here's why, and how to move yours.
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