Eating less protein may slow aging and improve metabolism, major review finds
A major review of over 350 studies suggests eating less protein may slow aging and improve metabolism. Researchers at the University of Wisconsin-Madison found lower protein intake is linked to reduced cellular damage and better metabolic function, partly via the hormone FGF21. While some groups need more protein, the findings suggest many sedentary adults consume too much, challenging recent US dietary guidance.
Protein restriction benefits
▪A review of over 350 studies suggests that many people may benefit from eating less protein, which could contribute to a longer life.
▪The review, published July 31 in Cell Press Blue, was conducted by researchers at the University of Wisconsin-Madison.
▪Protein restriction is considered a more feasible alternative to long-term calorie restriction for improving health and longevity.
Metabolic improvements
▪In human clinical trials, individuals who lowered their protein intake lost weight and body fat and showed improved fasting blood sugar.
▪Across the reviewed research, lower protein intake was consistently linked to better metabolic function.
Cellular aging mechanisms
▪The review concluded that protein restriction can limit cellular damage and help cells maintain normal function, potentially slowing aging.
▪Reducing protein intake can also alter the way cells react to nutrients.
FGF21 hormone effects
▪In mouse studies, elevated levels of FGF21 were linked to a longer lifespan, particularly in male mice.
▪FGF21 can raise energy expenditure, improve blood sugar regulation, and reduce inflammation.
▪The hormone fibroblast growth factor 21 (FGF21) increases in the body when protein intake falls.
Amino acid pathways
▪Excessive intake of certain amino acids may activate biological growth pathways that increase the risk of obesity and inflammation.
▪Specific amino acids that are the building blocks of protein, such as methionine, isoleucine, and valine, appear to play important roles in aging.
Individual protein needs
▪Groups such as pregnant women, certain older adults, and athletes often require more protein than sedentary individuals.
▪Updated US dietary guidance in 2026 recommends daily protein consumption of 1.2-1.6 grams per kilogram of body weight, nearly twice the previous amount.
▪Higher protein intake can support weight loss and help older adults preserve muscle, particularly when combined with exercise.
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