Moderate protein intake may boost longevity by influencing metabolism and cellular cleanup

An analysis published in Cell Press Blue examined how a modest reduction in protein intake influences processes tied to healthy aging. In animal experiments, scientists cut protein enough to avoid deficiency yet still provide sufficient amino acids, resulting in decreased adiposity, increased energy use and, in some cases, notably longer lifespans. Experiments that limited individual amino acids—such as isoleucine, valine or methionine—produced similar longevity gains, a response that may involve the hormone FGF21, which raises energy expenditure, helps regulate blood sugar and dampens inflammation.

Early human trials of reduced protein diets showed participants losing weight and body fat, along with lower fasting glucose or better insulin sensitivity over periods of weeks. While these findings are promising, the analysis cautions that protein is still vital for muscle growth and adaptation to training, and that definitive evidence of lifespan extension in people is lacking.