What it is
Intermittent fasting (IF) — including time-restricted eating and alternate-day approaches — cycles between periods of eating and not eating, focusing on *when* you eat rather than only *what*.
Why it matters for longevity
Fasting periods shift the body toward fat-burning and switch on repair programmes such as autophagy, overlapping mechanistically with caloric restriction and reduced mTOR signalling — the best-studied levers in ageing biology.
What the evidence shows
Human trials show IF can improve weight, insulin sensitivity and some cardiometabolic markers, often comparable to standard calorie reduction. Whether it independently extends human lifespan is unproven, and benefits depend heavily on diet quality and adherence.
What to ask a clinic
IF is not for everyone (for example a history of disordered eating, pregnancy, or medications such as insulin). Personalised guidance matters more than any fixed protocol.