Exercise, and specifically progressive strength training, has the strongest scientific backing as a brake on biological ageing. A Mediterranean dietary pattern, sufficient sleep and avoiding smoking, excessive alcohol and chronic stress reinforce that effect, but most studies in those areas are associative in nature. Anyone wishing to influence their biological age has the most concrete and well-supported starting point in structured, regular exercise.
Of all lifestyle factors, physical exercise has the strongest and most consistent evidence when it comes to slowing biological ageing. Multiple studies show that physical activity inhibits cellular and molecular ageing processes and extends healthy life years. Progressive strength training, in which the load increases gradually, is the most well-supported approach for older adults: it is indispensable for preserving muscle mass and reducing frailty, muscle loss (sarcopenia) and bone loss. Programmes that combine aerobic training, strength, balance and flexibility with cognitive exercises (so-called dual-task training) also improve both physical and cognitive fitness and reduce the risk of falls.
Nutrition is the second pillar. The Mediterranean diet and forms of dietary restriction (caloric reduction) have beneficial effects on metabolism and can slow biological ageing and cardiovascular disease. The evidence here is primarily associative: the studies show associations, but not hard cause-and-effect relationships. Specific supplements and individual nutrients show mixed results: sometimes encouraging, sometimes disappointing. A healthy dietary pattern rich in proteins, fibre, polyphenols and unsaturated fatty acids also promotes the diversity of gut bacteria, which contributes to better immune protection and muscle performance.
On the other side of the scale are factors that demonstrably accelerate biological ageing. Sedentary behaviour, sleep problems, a high-fat diet and psychosocial stress disrupt the body's system for detecting and processing nutrients, and increase the risk of cardiovascular disease. Smoking, alcohol use, UV radiation, air pollution and an unhealthy diet further accelerate ageing through oxidative stress (damage caused by free radicals) and telomere shortening, visible as wrinkles and loss of skin elasticity, but also measurable at the cellular level.
Sleep and mental health are two factors that receive relatively less attention in the research, yet nonetheless stand out. Poor sleep is associated with accelerated biological ageing and a higher risk of cognitive decline. In women who have experienced childhood trauma, a combination of an unhealthy lifestyle and mental health problems such as depression, anxiety and insomnia appears to accelerate biological ageing further, as measured by telomere length. This association was not found in men in the studied group.
Biological age can also be measured using so-called epigenetic clocks, which estimate how old your body is biologically based on DNA methylation patterns. Diet, exercise and level of education are all associated with this measure of biological age, although the direction and strength vary by factor. This underlines that biological ageing is influenced by multiple lifestyle factors simultaneously, and cannot be fully controlled by any single adjustment.
All claims are based on the provided PMIDs (39743381, 34836334, 37944707, 39604792, 34203776, 38704685, 28202822). The evidence for exercise is the strongest (causal or likely causal); for nutrition and other factors it is largely associative.