What you eat has a major effect on long‑term health, and adopting a longevity‑focused eating pattern can make a large difference — the earlier you start, the greater the potential benefit.

Many long‑lived people are asked about their secrets, and their answers often point to food. Some cite simple daily habits — modest dairy, olive oil, fruit, or the occasional treat — but the key question for the rest of us might be what they avoided. Diet influences the risk of the major conditions that shorten lives, so changes to what we eat can change how long we live.

Evidence from large datasets

Researchers led by Lars Fadnes at the University of Bergen used data from the Global Burden of Disease Study to model how shifting from a typical Western pattern (high in refined grains, added sugars, red and processed meats and low in wholegrains, fresh fruit, vegetables, nuts and fish) to a diet dominated by wholegrains, fruit, vegetables, nuts, legumes and fish would affect life expectancy. Their modelling suggests substantial gains. For example, a 20‑year‑old woman in the US eating a typical diet could expect to live to about 80 on current patterns, but switching permanently to the healthier pattern raises that projection to roughly 89 — nearly a decade extra. A 20‑year‑old man making the same change could see an increase from about 76 to 86.

The researchers found the biggest positive effects come from increasing wholegrains, nuts and legumes while cutting down on sugary foods and processed and red meats. Even partial improvements — moving only partway toward the ideal diet — still deliver measurable benefits.

Real‑world studies support the message Longitudinal and population studies back up the modelling. A team led by Zhaoli Dai‑Keller at the University of New South Wales examined the diets of people aged 95 and over who were still living in their communities across East Asia, Australia and western Europe. Those who reached very old age in good health tended to have varied, balanced diets — plenty of vegetables, fruit, fish, legumes and lean white meats — and lower alcohol intake. One consistent difference was lower salt consumption, which matters because excess sodium is a known contributor to cardiovascular disease.

A separate long‑term analysis by Anne‑Julie Tessier and Marta Guasch‑Ferré at Harvard re‑examined data from more than 105,000 participants followed from the mid‑1980s into later life to identify factors linked with “healthy ageing” (reaching age 70 without major chronic disease and remaining physically and mentally fit). Only about one in ten met those criteria, and sustained adherence to Mediterranean‑style eating patterns across middle age was a common feature among that group. Conversely, diets high in fatty, salty and processed meats were associated with poorer ageing outcomes.

Body weight and functional ability

Diet interacts with body weight in complex ways. In the UNSW study, people who reached 95+ tended to be slim: roughly half were in the normal‑weight range and about a third were underweight. While obesity clearly raises disease risk, being slightly overweight (but not obese) in later life was linked with better day‑to‑day functioning compared with being normal weight; being underweight raised the risk of impairment by around 25 per cent in some analyses. These findings help explain why extreme calorie restriction, which reliably extends lifespan in many laboratory animals, is controversial in humans: it is difficult to sustain, and any potential lifespan gains could come at the cost of frailty or reduced function.

Putting it into practice

Clinical trials that directly test a “longevity diet” in people would take decades to complete, so current conclusions rely on modelling and long‑term observational data. Still, converging lines of evidence point to practical, widely applicable advice: favour wholegrains, lots of plant foods (fruit, vegetables, legumes, nuts), moderate amounts of fish and lean proteins, cut back on added sugars and processed/red meats, and keep salt and excess calories in check. Even modest shifts toward these patterns, at almost any age, are likely to improve health and increase your odds of a longer, healthier life.

Adapted from the New Scientist article by Graham Lawton, “The science revealing how the right diet can add a decade to your life” (original article by Graham Lawton, 16 September 2025; updated 5 November 2025).

Graham holds a first-class honours degree in biochemistry and an MSc in science communication, both from Imperial College London