Researchers found that reducing protein intake may slow biological aging by improving metabolism, lowering inflammation, reducing cellular damage, and preserving healthy cell function. Previous research has demonstrated that lower protein intake can extend lifespan in flies and rodents. One of the main biological mechanisms involves fibroblast growth factor 21 (FGF21), a hormone that rises when protein intake is low. Pregnant women, highly active individuals, and some older adults may require higher protein intake. Although the review supports the potential benefits of moderate protein restriction for healthy aging, it does not recommend that everyone reduce protein intake.