Hormones regulate virtually every process in the body — from metabolism and muscle growth to mood, bone density and reproductive function. The hormonal changes of ageing are among the most significant physiological shifts most people will experience, and they begin earlier than most people realise.
Testosterone levels in men peak in the late teens to early 20s and begin a gradual decline from around age 30 — typically 1–2% per year. By age 70, most men have testosterone levels roughly 30–50% below their youthful peak. This contributes to reduced muscle mass, increased body fat, lower energy, and changes in libido and mood.
Unlike many age-related changes, testosterone decline is substantially modifiable. Regular resistance training, adequate sleep, maintaining healthy weight, and limiting alcohol are all associated with meaningfully higher testosterone levels at any age.
The female hormonal timeline is more sharply punctuated than the male equivalent. Oestrogen levels begin to decline from the late 30s, with the most rapid drop occurring in the years around menopause (UK average age: 51). This decline drives a wide range of changes including bone density loss (accelerated by up to 2–3% per year in the first years post-menopause), changes in cardiovascular risk profile, and the well-known vasomotor symptoms.