The things that are not a product.

How long people habitually sleep, followed in cohorts of millions. Both short and long sleep track with earlier death and more heart disease, with the lowest risk around seven hours. Short sleep has a plausible mechanism; long sleep is probably a marker of illness.

What happens when healthy people are made to sleep less, in the lab. Two weeks at six hours a night degrades attention as much as two nights with no sleep, and the people affected do not feel it. An extra hour improved short sleepers' sleep but, in one trial, not metabolism.

Lifting against resistance, followed in cohorts of hundreds of thousands. Any amount is associated with 15 to 20% lower mortality, the lowest risk sits around an hour a week, and the benefit adds to aerobic exercise. Above a couple of hours a week the curve flattens or turns.

Movement that raises the heart rate, measured in 30 million people by questionnaire and tens of thousands by accelerometer. Going from nothing to the recommended 150 minutes a week is associated with about a third lower mortality. Above that the gains shrink.

How much protein to eat, as opposed to which powder. More protein adds small muscle and strength gains with resistance training, with a threshold near 1.6 g per kg a day in younger adults. Cohorts link animal protein to slightly higher mortality, plant protein to lower.

Eating within a window or fasting on set days. It produces weight loss, and in head-to-head trials about the same as simply eating less. Alternate-day fasting edges ahead by about a kilogram in a 2025 network meta-analysis. The metabolic benefits beyond weight are small.

A pattern built on olive oil, vegetables, legumes, fish and nuts. One of the few diets tested in large randomized trials with hard outcomes: it reduced heart attacks and strokes by about 30% in primary prevention and beat a low-fat diet in secondary prevention over seven years.

Structured attention training, usually an eight-week program. Trials with active controls find small to moderate reductions in anxiety, depression and pain, and no advantage over established treatments. In healthy people the effect on stress is moderate and lasts.

Ice baths, plunges and cold showers. For recovery the trials support a small benefit for soreness and power within a day. For building strength, a 2015 trial found cold water after lifting blunted the gains. For health and mood the evidence is early.

Regular dry heat, studied mostly in one Finnish cohort of middle-aged men, where frequent and longer sessions went with less sudden cardiac death, hypertension and dementia. One small randomized trial found sauna after exercise lowered blood pressure more than exercise alone.