Your 40s — Screen & Stack
The screening decade
At {chronoAge} your diseases of aging are starting to whisper. Atherosclerosis is quietly progressing — often for 20 years before a first cardiac event. Hormone shifts are picking up. This is when proactive screening pays the biggest dividends vs waiting for symptoms.
CAC score: the earliest cardio signal
Coronary artery calcium scoring (a 10-minute CT scan, often under $150) quantifies plaque years before symptoms. A score of 0 at 45 is strongly protective; a score over 100 means aggressive intervention is warranted. Most people don't know their number.
Hormones start shifting
Testosterone falls ~1% per year from about 30 onwards. Perimenopause begins at 40–45 on average for women. Both affect mood, body composition, libido, sleep, and cognition — in ways that are measurable and often treatable with proper evaluation.
The stack starts earning its keep
This is the decade where a supplement stack actually moves the needle. Creatine (muscle + cognition), magnesium glycinate (sleep + glucose), omega-3 (cardio), vitamin D (if deficient), collagen (tendons) are the high-evidence anchors. Peptides enter the conversation for some.
Cancer screening starts now (or earlier)
Colonoscopy starts at 45 (down from 50 — early-onset colon cancer is rising). Mammogram baseline at 40 (or earlier with family history). LDCT lung scan if smoking history. PSA discussion at 45-50. Skin check annually. Most cancer caught at stage 1 has >95% 5-year survival; the same disease at stage 4 sits at 5-25%. Screening is the single highest-leverage 40s habit and most adults skip or delay it.
Key Takeaway
Your 40s is the screening decade. CAC score, full lipid panel, hormone workup, DEXA. Pair early detection with the highest-evidence supplement + training stack and you'll enter 50 with a very different trajectory than the average.