Ask ten longevity enthusiasts what increases lifespan the most and you will get ten different answers: metformin, rapamycin, cold plunges, NAD boosters, fasting. The published evidence gives a much less exciting, much more useful answer. The single biggest lever ever measured in humans is quitting smoking, worth about a decade of life. Stack five ordinary habits together and American data puts the gain at 12 to 14 years from age 50. Everything else, from exercise to blood pressure drugs, slots in below those two, and the fashionable pharmacological biohacks have no human lifespan data at all. Here is the honest ranking, with the numbers and the studies behind each entry.

The short answer

Quitting smoking increases lifespan the most of any single intervention studied in humans. Smokers lose roughly 10 years of life expectancy compared with people who never smoked, and quitting before age 40 avoids about 90% of that excess mortality. The largest total gain comes from stacking five low-risk habits (not smoking, daily activity, a healthy diet, a healthy weight, modest alcohol): in a major US study, people who had all five at age 50 lived 14.0 years longer (women) and 12.2 years longer (men) than people who had none. No supplement, drug or gadget has human evidence anywhere near these numbers.

How this ranking was built

One warning before the list. No trial has ever tested every longevity intervention head to head, so a perfectly clean ranking is impossible. Studies differ in design, population and era: some are randomised trials, some are decades-long observational cohorts, and the numbers are not directly interchangeable. This ranking orders interventions by the size of the effect reported, weighted by the strength of the evidence, and it says plainly where the comparison is imperfect. Randomised trials outrank observational cohorts; large cohorts with long follow-up outrank small ones; and anything tested only in animals sits in a separate section at the end, because mice are not people.

1. Quit smoking, or never start: about a decade of life

The largest single effect on lifespan in the human literature belongs to smoking. In the landmark US study by Jha and colleagues, published in the New England Journal of Medicine in 2013, current smokers had about 10 years less life expectancy than people who had never smoked. The benefit of quitting scaled with earliness: people who quit between ages 25 and 34 gained about 10 years of life compared with continued smokers, those who quit at 35 to 44 gained about 9 years, and those who quit at 45 to 54 gained about 6 years. Quitting before age 40 reduced the excess mortality risk of continued smoking by roughly 90%. The parallel UK study of one million women, by Pirie and colleagues in The Lancet, found the same decade of life lost and the same 90%-plus avoidance from quitting before 40.

This is not old news being recycled. A 2024 update in NEJM Evidence, analysing 1.48 million adults across the United States, the UK, Canada and Norway over 15 years, confirmed the scale: current smokers had nearly triple the mortality risk of never smokers and lost 12 to 13 years of survival between ages 40 and 79. Quitting for fewer than three years already averted about five years of life lost, and quitting for ten or more years averted about ten, returning survival close to that of never smokers. The authors’ message was blunt: it is never too late to quit, and the benefits start within years. No biohack on the market has a credible claim to a ten-year gain.

2. Stack the five basics: 12 to 14 extra years at 50

The biggest total gain ever quantified comes from combining five ordinary habits. Li and colleagues, in Circulation in 2018, analysed the Nurses’ Health Study and the Health Professionals Follow-up Study, 42,167 deaths over up to 34 years, and projected life expectancy in the US population using national survey and mortality data. The five low-risk factors were: never smoking, a healthy diet (in the top 40% of diet quality scores), at least 30 minutes a day of moderate to vigorous activity, a body mass index between 18.5 and 24.9, and moderate alcohol intake (5 to 15 grams a day for women, 5 to 30 for men).

The results: at age 50, women with all five factors could expect to live 14.0 more years than women with none, and men 12.2 more years. People with all five had 74% lower all-cause mortality during the study period, with a hazard ratio of 0.26 versus zero factors. The authors estimated that failing to adopt the five factors accounted for about 61% of all premature mortality in the population. The gains were also additive: each additional healthy factor added roughly two years. This study is the strongest answer to “what increases lifespan the most” in aggregate terms, and its five factors reappear, one by one, in the rest of this ranking.

3. Move every day: up to 39% lower mortality

Exercise is the most studied longevity lever of all, and the dose-response is now well mapped. Arem and colleagues pooled six prospective cohorts, 661,137 men and women with 116,686 deaths over a median 14.2 years, in JAMA Internal Medicine in 2015. Compared with people reporting no leisure-time activity, those doing less than the guideline minimum of 7.5 metabolic-equivalent hours a week had 20% lower mortality; those at one to two times the minimum had 31% lower; at two to three times, 37% lower; and the benefit plateaued at three to five times the minimum with 39% lower mortality. There was no evidence of harm even at ten or more times the recommended minimum.

The practical reading: the US guideline minimum, roughly 150 minutes of moderate activity a week, is associated with about a 31% lower risk of death versus doing nothing, and even below-minimum activity delivered a real 20% reduction. The curve is steepest at the bottom, which means the biggest return goes to people who currently do nothing. A similar dose-response held for cardiovascular and cancer mortality specifically.

4. Eat Mediterranean-style: about 30% fewer major cardiovascular events

Diet is harder to test than exercise, but one trial stands above the rest. PREDIMED randomised 7,447 Spanish adults aged 55 to 80, all at high cardiovascular risk but without established disease, to a Mediterranean diet supplemented with extra-virgin olive oil, the same diet supplemented with mixed nuts, or advice to follow a low-fat diet, for a median of 4.8 years. The Mediterranean groups had about 30% fewer major cardiovascular events, heart attacks, strokes and cardiovascular deaths, with hazard ratios of 0.69 for the olive oil group and 0.72 for the nuts group.

Honesty requires one footnote: the original 2013 paper was retracted after randomisation irregularities were found at some sites, where participants were assigned by household rather than individually. The corrected republication in 2018, with the analysis adjusted for the problem, preserved the main result. It is the 2018 version that should be cited. Cardiovascular disease is the world’s leading killer, so a 30% reduction in major events is a genuine longevity lever, though this trial measured events rather than lifespan directly.

5. Control blood pressure properly: 27% lower all-cause mortality

High blood pressure is one of the largest contributors to premature death worldwide, and the SPRINT trial showed how much aggressive control matters. More than 9,300 adults aged 50 and over with high cardiovascular risk but no diabetes were randomised to an intensive systolic target below 120 mmHg or a standard target below 140 mmHg. Published in the New England Journal of Medicine in 2015, the trial found 25% fewer cardiovascular events and 27% lower all-cause mortality in the intensive group, including 43% fewer cardiovascular deaths. A later actuarial analysis estimated that intensive control added about 2.9 years of residual life expectancy at age 50.

The caveats matter. The trial ran for just over three years on average, enrolled people at high risk, and intensive treatment brought more adverse events: low blood pressure episodes, fainting and acute kidney injury, though with no evidence of permanent kidney damage. This is a lever for people with hypertension, applied with a doctor, not a DIY longevity trick. But for the population it fits, the mortality reduction is among the largest ever seen for a drug intervention.

6. Sleep around seven hours, not four and not ten

Sleep has a U-shaped relationship with mortality: both short and long sleep are associated with higher risk, and the bottom of the curve sits at around seven hours a night in most large meta-analyses. The mechanism is still debated, and long sleep in particular may partly reflect underlying illness rather than cause it, so this evidence is observational and weaker than the trial data above. What is consistent is that chronic short sleep is tied to higher cardiovascular and metabolic risk. If you want the sleep side of this ranking dialled in precisely, this site’s earlier analysis of the sleep-duration window, based on large cohort data, is the natural companion piece. The practical target that keeps recurring across studies is roughly seven to eight hours.

7. Keep alcohol modest: the roughly 100-gram-a-week threshold

The alcohol story has shifted against drinking. Wood and colleagues analysed 599,912 current drinkers across 83 studies and published the result in The Lancet in 2018: drinking above about 100 grams of alcohol a week, roughly five to six UK standard drinks, was associated with shorter life expectancy, with the loss growing as intake rose. Below that threshold there was no clear safe level for all outcomes, and the analysis found no overall mortality benefit from drinking. This is observational evidence with the usual caveats, and it is one reason the “moderate alcohol” factor in the five-habit study above should be read as “little or none is fine too”.

8. Stay socially connected: a 50% survival edge

The most underrated lever in longevity discussions is other people. A 2010 meta-analysis in PLoS Medicine by Holt-Lunstad and colleagues pooled 148 studies with 308,849 participants and found that people with stronger social relationships had a 50% increased likelihood of survival over the follow-up periods, an odds ratio of 1.50. In the authors’ own comparison, the magnitude sat alongside quitting smoking and ahead of obesity and physical inactivity. Social connection is hard to randomise, so this remains observational, but the consistency across nearly 150 studies is difficult to dismiss. Loneliness is not just unpleasant; in the data it behaves like a risk factor.

What about calorie restriction, rapamycin and metformin?

This is where the biohacker conversation usually starts, and where the evidence is thinnest. Calorie restriction extends lifespan in organisms from yeast to monkeys: in rhesus macaques, long-term studies at the US National Institute on Aging and the University of Wisconsin found delayed age-related disease, though the two studies disagreed on lifespan itself. In humans, the CALERIE trial randomised 218 healthy non-obese adults to two years of roughly 25% calorie restriction and found improved cardiometabolic risk markers, but nobody has shown that calorie restriction extends human lifespan, and sustained 25% restriction is not a lifestyle most people will maintain.

Rapamycin extended lifespan in genetically diverse mice even when started late in life, in the well-known 2009 Nature study from the Interventions Testing Program. That is a genuine, replicated result in mice. It is not a result in humans, and rapamycin suppresses the immune system, which is a serious trade-off. Metformin has intriguing observational signals in diabetics, and the TAME trial (Targeting Aging with Metformin) aims to test whether it delays age-related disease in non-diabetics, but the trial is still the test, not the proof. The supplement shelf is thinner still: compounds like NMN and NR reliably raise NAD+ levels in blood, but no supplement has randomised human evidence of extending lifespan. Anyone selling you a longevity pill with a ten-year claim is selling something the data does not contain.

The ranked list, in one place

Ordered by the size of the reported effect, with evidence quality in brackets:

1. Quit smoking: ~10 years of life regained (large cohorts, replicated across countries, updated in 2024).
2. All five healthy habits together: 12 to 14 years at age 50 (large US cohorts, modelled life expectancy).
3. Regular exercise: 31 to 39% lower mortality (pooled cohorts, 661,000 people; dose-response mapped).
4. Mediterranean-style eating: ~30% fewer major cardiovascular events (randomised trial, 7,447 people).
5. Intensive blood pressure control: 27% lower all-cause mortality (randomised trial, high-risk hypertensives).
6. Sleeping around seven hours (observational, U-shaped; weakest causal claim in the top tier).
7. Keeping alcohol near or below ~100 g a week (observational, 600,000 drinkers).
8. Strong social relationships: ~50% higher odds of survival (meta-analysis of 148 studies; hard to randomise).
9. Calorie restriction, rapamycin, metformin, longevity supplements: unproven in humans (animal data or ongoing trials only).

The pattern is unglamorous and that is the point. The interventions with the biggest measured effects on human lifespan are behaviours and basic medicine, not molecules. The biohack worth the most is the one with a randomised trial or a million-person cohort behind it, and right now those all point at the same boring list: do not smoke, move daily, eat like the Mediterranean, keep your blood pressure down, sleep seven hours, drink little, and keep your friends close.

Related reading

• Can Habit Stacking Add Years to Your Life? The 60,000-Person Study: the stacking idea from this ranking, tested in a different large dataset.
• Two Strength Tests That Predict Your Longevity (and How to Hit the Top Quartile): why strength, the thing exercise builds, shows up in mortality data.
• The 6.4 to 7.8 Hour Sleep Window: Dialling In Your Longevity Sweet Spot: the sleep entry in this ranking, in full detail.

Sources

• Jha P. et al. 21st-Century Hazards of Smoking and Benefits of Cessation in the United States. New England Journal of Medicine. 2013;368:341-350. https://doi.org/10.1056/NEJMsa1211128
• Jha P. et al. Smoking Cessation and Short- and Longer-Term Mortality. NEJM Evidence. 2024. Summary: https://www.medicine.net/news/Health_science/Quitting-smoking-at-any-age-brings-big-health-benefits-fast-Study.html
• Li Y. et al. Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population. Circulation. 2018;138:345-355. https://repub.eur.nl/pub/114282/
• Arem H. et al. Leisure Time Physical Activity and Mortality: A Detailed Pooled Analysis of the Dose-Response Relationship. JAMA Internal Medicine. 2015;175(6):959-967. https://pmc.ncbi.nlm.nih.gov/articles/PMC4451435/
• Estruch R. et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. New England Journal of Medicine. 2018;378:e34 (republication). Summary: https://www.healio.com/news/primary-care/20180614/mediterranean-diet-effective-for-primary-prevention-of-cvd
• SPRINT Research Group. A Randomized Trial of Intensive versus Standard Blood-Pressure Control. New England Journal of Medicine. 2015;373:2103-2116. Long-term survival analysis: https://jamanetwork.com/journals/jamacardiology/fullarticle/2761951
• Wood A.M. et al. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599,912 current drinkers in 83 prospective studies. The Lancet. 2018;391:1513-1523.
• Holt-Lunstad J. et al. Social Relationships and Mortality Risk: A Meta-analytic Review. PLoS Medicine. 2010;7(7):e1000316.
• Ravussin E. et al. A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity. The Journals of Gerontology. 2015.
• Harrison D.E. et al. Rapamycin fed late in life extends lifespan in genetically heterogeneous mice. Nature. 2009;460:392-395.

Frequently asked questions

What increases lifespan the most?

Quitting smoking is the single most powerful intervention ever measured in humans, worth about a decade of life. The largest total gain, 12 to 14 years from age 50, comes from stacking five habits: not smoking, daily activity, a healthy diet, a healthy weight and modest alcohol intake.

Can one habit really add 10 years to your life?

Quitting smoking comes closest. Smokers lose roughly 10 years of life expectancy versus never smokers, and quitting before 40 avoids about 90% of that excess risk. The gain is measured against continued smoking, not against a perfect baseline.

What is the single best longevity intervention after quitting smoking?

Regular exercise has the strongest evidence base after smoking cessation: in a pooled analysis of 661,137 adults, meeting activity guidelines was linked to about 31% lower mortality, with benefits rising to 39% at higher volumes and no sign of harm from very high volumes.

Is exercise more important than diet for longevity?

They work on different risks and the evidence is not directly comparable. Exercise has the larger and better-mapped mortality dose-response, while the Mediterranean diet has the strongest randomised trial evidence for preventing cardiovascular events, at about 30% fewer major events. The five-habit study suggests the honest answer is both.

Can you outrun a bad diet or out-supplement a bad lifestyle?

The data says no. In the five-factor study, the 12 to 14 year gain required the full stack, and each added factor contributed roughly two years. No supplement has human evidence of extending lifespan, and the much-hyped drugs (rapamycin, metformin) have only animal data or ongoing trials.

What increases lifespan the most after age 50?

The same list applies, with blood pressure control gaining importance: the SPRINT trial found intensive blood pressure control cut all-cause mortality by 27% in adults over 50 at high cardiovascular risk, translating to roughly three extra years of life expectancy at age 50.