Fasting explained: How skipping meals might impact your lifespan

Fasting, the voluntary practice of abstaining from food for a set period, has become increasingly popular for its potential health benefits.

According to research published in Endocrine Reviews via Oxford Academic, these effects have been observed in both humans and animal models, showing promise for improving overall health.

The study says that fasting activates important biological pathways that support metabolism, cellular repair, and possibly even longevity

When the body goes without food, it undergoes a series of metabolic changes. Initially, glucose from recent meals is used for energy, followed by stored glycogen.

Eventually, the body shifts to burning fat and producing ketones. The study says this metabolic shift improves insulin sensitivity, reduces inflammation, and enhances mitochondrial function, all of which are linked to slower ageing.

Fasting and lifespan

The research explains that fasting may influence lifespan through several key mechanisms.

One of the most important is autophagy, a process in which cells remove damaged proteins and organelles, helping to prevent age-related diseases such as heart conditions, diabetes, and neurodegeneration.

Fasting also shifts energy metabolism, lowering oxidative stress and inflammation, which are major contributors to ageing.

Hormonal changes, such as reduced insulin and growth hormone activity during fasting, may further support longevity.

Additionally, fasting can affect gene expression and epigenetic markers linked to ageing, helping cells function more efficiently over time.

Animal studies show that regular fasting can extend lifespan by 20–30%, mainly by reducing disease risk and improving metabolic function.

In humans, the study says that early evidence suggests fasting improves health markers tied to longevity, such as blood pressure, cholesterol, and glucose control, though long-term studies are still needed to confirm whether it directly increases lifespan.

How long should you fast?

Fasting can be practised in several ways. Intermittent fasting, also called time-restricted feeding, involves eating within an 8–10 hour window and fasting for the remaining 14–16 hours each day.

According to the study, this is the most practical approach for humans and has been associated with better blood sugar control and improved metabolic health.

Alternate-day fasting, in which people eat normally one day and restrict calories the next, may also help reduce inflammation and support healthy cholesterol levels.

Longer fasts, such as 24–48 hours, done periodically, have shown strong benefits in animal studies by activating deeper cellular repair mechanisms, though experts recommend such fasts in humans only under medical supervision.

While fasting offers potential benefits, it is not risk-free. Extended or extreme fasting can affect bone density, immunity, and reproductive health in some individuals.

The study emphasises that fasting should be approached carefully and, when necessary, under medical supervision, particularly for those with existing health conditions.

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