Eating less protein could slow aging, major review finds
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- Dudley Lamming and Bailey A. Knopf at the University of Wisconsin-Madison published the review in Cell Press Blue on July 31, 2026, synthesizing 350+ studies on protein restriction and aging.
- The review identified four recurring mechanisms: better metabolic function, altered nutrient signaling, reduced cellular damage, and improved maintenance of healthy cells in response to lower protein intake.
- FGF21, a hormone that rises when protein intake falls, was linked to longer lifespan in mice — with the effect stronger in males — and human studies confirm FGF21 increases on lower-protein diets.
- Methionine, isoleucine, and valine, three specific amino acids, appear to drive aging-related pathways when consumed in excess, the review found, by activating growth signals that may increase obesity and inflammation risk.
- Human clinical trials cited in the review found people who lowered protein lost weight and body fat and improved fasting blood sugar, in some cases while consuming more total calories.
- The review comes as updated US dietary guidance this year nearly doubled recommended protein intake to 1.2–1.6 grams per kilogram of body weight (0.5–0.7 g/lb) — guidance Lamming argues should be personalized by age AND physical activity level rather than applied uniformly.
- Lamming notes that athletes tolerate high protein intake without metabolic harm, likely because exercise directs protein toward muscle, meaning sedentary adults face different risks from the same intake.
Why it matters: The review directly contradicts this year's US dietary guidance, which nearly doubled recommended protein to 1.2–1.6 g/kg — meaning the protein-fortified foods crowding grocery shelves may be oversold to the majority of sedentary adults. Lamming's call for activity-personalized recommendations puts the blanket 'more protein' trend at odds with the evidence for non-athletes.
