Changing your diet at 20 can add more than 10 years to your life expectancy
A study published in PLOS Medicine in 2022 modelled the impact of a sustained dietary change on life expectancy. Switching from a typical Western diet to an optimal diet at age 20 extends life by 10.7 years for women and 13 years for men.
The link between diet and longevity is well established. Less well known is the scale of the gains measured when that dietary change is modelled rigorously and sustained over time.
A team of Norwegian and American researchers published a 2022 analysis in PLOS Medicine using US mortality data, simulating the effect of a shift from a typical Western diet to an optimal diet at different ages. At age 20, the gain in life expectancy reaches 10.7 years for women and 13 years for men. At age 60, the benefit remains substantial: 8 years for women, 8.8 years for men.
The greatest gains come from three simple changes: eating more legumes (+2.5 years for men), more whole grains (+2.3 years), and more nuts (+2 years), whilst reducing red and processed meat. The modelled optimal diet is not an extreme restriction — it resembles a Mediterranean diet with more legumes.
What this study points to is not individual guilt but structural potential. A more plant-based diet, accessible and affordable, is one of the most powerful public health levers available — and one of the least costly to activate at scale.
Further reading: What Blue Zones Teach Us About Longevity