Nutrients in food mimic calorie restrictions. Can they improve our health?

Scroll through social media and you will soon encounter advice about living longer, from fasting plans and supplements to elaborate daily routines. Yet reaching an advanced age tells us little about how healthy or independent those later years will be.

Researchers often use the term healthspan for the years spent in good health, free from disability or chronic disease. In 2021, global life expectancy was 71.4 years, while healthy life expectancy was 61.9 years, according to the World Health Organization (WHO). That represents a gap of nine and a half years. A separate analysis estimated that this gap widened in 203 of 204 countries and territories between 1990 and 2023.

The WHO takes a broader view of healthy ageing, focusing on the abilities that allow people to do what they value, such as undertaking daily tasks, maintaining relationships and contributing to society. This recognises that people can live well while managing a health condition. “Functional healthspan” describes how long someone maintains the capacities needed for independent living.

As we age, declining muscle strength and mass, reduced aerobic fitness and even “inflammaging” (or low-grade inflammation) become more prevalent. These changes vary considerably between people. Diet, physical activity and sleep can influence how well we age, although income, housing, healthcare and the wider environment also play important roles.

Why researchers study calorie restriction

One intensively...

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