Protein restriction linked to longevity benefits for sedentary adults, review finds
A review of over 350 studies suggests that lowering protein intake, rather than cutting calories, may improve metabolism and health markers in inactive adults, though human trials are still needed.
A review of more than 350 studies published in the journal Cell Press Blue indicates that reducing dietary protein could provide metabolic advantages similar to calorie restriction for people who lead sedentary lifestyles. The analysis found that lower protein consumption was associated with improved metabolic signaling, less cellular damage and enhanced cellular maintenance, effects that appear to be mediated by the hormone fibroblast growth factor 21 (FGF21).
FGF21 levels rise when protein intake is limited, and animal research has linked this surge to increased energy expenditure, reduced inflammation, better blood-sugar control and longer lifespan. The review highlighted three essential amino acids—methionine, isoleucine and valine—as potential contributors to aging pathways when consumed in excess by inactive individuals.
"It's absolutely crystal-clear that there are benefits of protein for muscle growth and exercise response of active individuals," said Dudley Lamming, the paper’s corresponding author and a researcher at the University of Wisconsin-Madison. "But because most people are relatively sedentary, many people are likely consuming more protein than they actually need, which probably has negative health consequences," he added.
The authors note that the findings are based on a synthesis of existing research and do not establish direct cause-and-effect relationships in humans. They call for longer-term clinical studies to determine whether the observed metabolic improvements translate into increased lifespan. The review also cautions that protein requirements vary by age, activity level and physiological condition, emphasizing that athletes, pregnant women and older adults may need higher protein intakes.