Does caloric restriction actually make your cells younger?

Caloric restriction slows down a broad range of ageing processes at the cellular level. Extensive rat studies examining individual cells across multiple tissues simultaneously showed that the typical changes associated with ageing - such as shifts in cell composition and disrupted gene expression - progressed noticeably more slowly. A complete reversal of ageing was not observed, but the slowdown was broad and consistent.

At the molecular level, several mechanisms can explain this. Caloric restriction appears to influence two central control switches in the cell: mTORC1, a growth signal that runs out of control during overconsumption, is inhibited, while AMPK, an energy sensor that activates repair processes, is switched on. As a result, the self-cleaning of damaged cellular components (autophagy) improves, mitochondria recover more effectively, and DNA damage accumulates more slowly. These effects have been convincingly demonstrated in animal research and cell studies; in humans, the findings are more limited.

In humans, the evidence is less advanced. Multiple studies show that caloric restriction and intermittent fasting reduce weight, improve insulin resistance, and favourably affect cardiovascular risk factors. These are measurable, health-relevant effects. However, whether this also means that your cells truly 'become younger' in a biological sense, and whether it extends lifespan, has not yet been proven in humans. Long-term randomised trials are lacking.

There are also risks to take into account. With very severe caloric restriction, vulnerability to infections may increase and wound healing may deteriorate. How large this risk actually is in humans has not yet been sufficiently studied. People with a low body weight, older adults, or people with a medical condition would do well to discuss this with their doctor before applying caloric restriction.