Research library

Everything your body needs to perform at its best.

30 topics, each with its own page: what it is, how it works in your body, how to measure it, the biggest studies, how to improve it, and the common myths.

Updated Oct 2026 · 111 new studies from 2025–26 → Test yourself: 300-card quiz →

Heart & fitness

Strong evidence VO2 max 5× higher risk of death for the least fit vs the fittest Good evidence Resting heart rate +9% risk of death for every extra 10 beats per minute Good evidence HRV +32–45% risk of a first heart attack or stroke with low HRV Strong evidence Cardio & steps −31% death risk at 150–300 min of moderate exercise a week Strong evidence Blood pressure 2× risk of dying from heart disease or stroke for every 20 mmHg higher (top number)

Strength & body

Strong evidence Muscle & strength +16% risk of death for every 5 kg weaker grip Good evidence Balance & mobility +84% risk of death for people aged 51–75 who couldn't stand on one leg for 10 seconds Good evidence Waist & body fat 2× risk of early death with a large waist vs a small one, even at the same BMI

Recovery & repair

Good evidence Sleep +12% risk of death sleeping under 6 hours a night Early evidence Fasting & autophagy 2016 Nobel Prize for discovering how autophagy works Early evidence Sauna & heat −40% death risk with 4–7 sauna sessions a week vs one Good evidence Recovery 1.7× injury risk in young athletes sleeping less than 8 hours a night

Food & life

Strong evidence Blood sugar −58% new diabetes in people with prediabetes who lost 7% of their weight and walked 150 min a week Strong evidence Food & fibre −30% heart attacks, strokes and heart deaths on a Mediterranean diet with olive oil or nuts Good evidence Friends & purpose +50% higher odds of staying alive for people with strong social ties Strong evidence Protein 1.6 g/kg of protein a day, the point where extra muscle gains from training level off Good evidence Supplements −22% autoimmune disease with 2,000 IU of vitamin D a day over 5 years Strong evidence Alcohol & smoking 10 yrs of life lost by lifelong smokers, almost all of it regained by quitting before 40

Mind & mood

Good evidence Stress 5 min a day of slow 'cyclic sighing' lifted mood more than mindfulness meditation Strong evidence Mental health 218 trials pooled: walking, jogging, yoga and strength training all eased depression Good evidence Brain & memory 45% of dementia linked to 14 changeable risk factors

Hormones & inner health

Good evidence Hormones −10–15% testosterone after one week of 5-hour nights in healthy young men Good evidence Gut microbiome 38 trillion bacteria in an average body, roughly one for every human cell Good evidence Longevity tests +70% 30-year heart risk in women with the highest inflammation (hsCRP)

Everyday body care

Good evidence Hydration +39% risk of chronic disease in adults with blood sodium above 142, a sign of too little fluid Strong evidence Skin −24% skin ageing over 4.5 years with daily sunscreen vs using it when people felt like it Good evidence Eyes & vision 50% of the world expected to be short-sighted by 2050 Good evidence Posture & back 619M people with low back pain worldwide, heading for 843 million by 2050

Tech & environment

Good evidence Wearables & AI 7k steps a day linked to 47% lower death risk; benefits keep rising more slowly after that Good evidence Light & environment +30% depression risk in people with the brightest nights; bright days cut it by about 20%