Most longevity content optimizes for the wrong target. Lifespan is heavily genetic and only modestly moved by intervention. Healthspan, the number of those years spent in good function, is mostly behavioral. The levers that move healthspan most are also the cheapest. They are also the most boring.
This piece ranks interventions by demonstrated effect on healthspan in human cohort studies and trials. We start at the bottom of the funnel because that is where most people overspend attention and underspend effort.
Which Tier 1 basics drive most healthspan variance?
Don't smoke. Smoking shaves roughly 10 years off life expectancy and starts cutting into healthspan a decade earlier. No supplement, peptide, or exotic protocol on this site outweighs continuing to smoke.
Move enough. Cohort data is consistent: people in the bottom 25% of cardiorespiratory fitness die earlier than people with metastatic cancer. Mandsager 2018 (n=122,007) found each 1-MET improvement in treadmill fitness associated with ~11% lower all-cause mortality ( Mandsager et al. 2018, n=122007 ). Going from "below average" to "above average" CRF reduced mortality hazard by 50% or more. No drug class approaches that. Start with Zone-2 cardio 3-4x/week and a strength session 2x/week. See Zone-2 and VO2 Max.
Sleep enough, regularly. Both short sleep and irregular timing independently predict cardiometabolic disease ( Besedovsky et al. 2019 ). Aim for 7-9 hours. Protect your sleep onset window within 30 minutes night-to-night. See Sleep Architecture.
Maintain muscle and bone. Sarcopenia and osteopenia drive the falls that drive the hospitalizations that end independent living. Resistance training is non-optional past 40. Protein intake around 1.6 g/kg/day supports hypertrophy and retention; Morton 2018 meta-analysis (n=1,863) shows the benefit curve flattens above that ( Morton et al. 2017, n=1863 ).
Manage cardiometabolic risk. ApoB, LDL particle count, blood pressure, fasting insulin, HbA1c. These are the numbers that drive every aging-related disease.
Tier 1 healthspan levers: largest single trial or cohort per category
| Study | N | Duration | Design | Outcome | Finding |
|---|---|---|---|---|---|
| Mandsager 2018 (CRF) cite | 122,007 | median 8.4 yr | Retrospective cohort, treadmill VO2 max as exposure | All-cause mortality | Each 1-MET higher CRF associated with ~11% lower all-cause mortality; bottom-quartile fitness was a stronger mortality predictor than smoking, diabetes, or hypertension |
| Besedovsky 2019 (sleep) cite | narrative review | n/a (review) | Mechanistic + epidemiologic review | Sleep, immune function, and chronic disease | Chronic short sleep and timing irregularity each independently associate with elevated cardiometabolic and immune dysfunction |
| Morton 2018 (protein and lifting) cite | 1,863 across 49 RCTs | trial range 6-52 wk | meta-analysis of resistance-training RCTs | Fat-free mass and 1RM strength | Plateau at ~1.6 g/kg/day; resistance training plus adequate protein protects lean mass through ageing |
| VITAL (Manson 2019) cite | 25,871 | median 5.3 yr | double-blind RCT (vitamin D3 2000 IU vs placebo) | Cancer and cardiovascular events | Null on primary endpoints; secondary cancer-mortality signal in subgroup analysis; reinforces 'supplement to a measured deficiency, not as a default' |
Synthesis The Tier 1 evidence base is unusual in that the effect sizes are large compared with most pharmaceutical interventions. Cardiorespiratory fitness alone moves all-cause mortality more than the combined effect of every Tier 3 longevity intervention currently under trial.
What Tier 2 additions help once the basics are dialed in?
Strength of social ties. Loneliness predicts mortality at roughly the magnitude of moderate smoking in cohort data. Hard to operationalize, but real.
Sun, but not too much. Vitamin D status (25-OH between 40 and 60 ng/mL is a reasonable target in most labs) and circadian light exposure both matter. Skin cancer also matters. VITAL (n=25,871) found D3 supplementation did not reduce cardiovascular or cancer incidence at 5 years, though a mortality signal appeared in secondary analyses ( Manson et al. (VITAL) 2019, n=25871 ). Ambient sun plus a multivitamin is good enough for most.
Targeted supplementation for documented deficiency. Magnesium, omega-3, B12, iron, vitamin D. Get tested. Supplement what is low. Don't supplement what isn't.
Which Tier 3 longevity interventions are worth the spend?
This is where most biohacker content lives, and where most biohacker spend goes. It belongs here because effect sizes are smaller and evidence is weaker. Worth exploring once Tier 1 is solid:
- GLP-1 receptor agonists. See GLP-1s Without the Hype. STEP 1 delivered ~14.9% weight loss at 68 weeks ( Wilding et al. (STEP 1) 2021, n=1961 ).
- Rapamycin. Mannick 2018 (n=264) showed TORC1 inhibition improved immune function in healthy elderly ( Mannick et al. 2018, n=264 ); decades-long healthspan benefit remains under-powered in humans.
- NAD+ precursors. Animal data suggestive; human RCTs mixed, effect sizes small.
- Senolytics. Promising preclinically. No positive RCT in humans yet as of 2026.
The counter-view
Not everyone weights these the same. Peter Attia argues Tier 3 interventions layered on top of Tier 1 compound into meaningful healthspan differences over 30 years. Matt Kaeberlein is more skeptical: human trials of "hot" longevity interventions have mostly underwhelmed, and the basics still win. Both are right about what they are right about. If your Tier 1 is unfinished, Attia would agree with Kaeberlein: finish Tier 1 first.
How to think about your own protocol
Rank every intervention by (effect size) × (evidence quality) ÷ (cost + complexity + risk). The ranking will look almost identical to the tiers above.
If you are spending more attention on Tier 3 than on Tier 1, your ranking is broken. Fix that first.
