Protein is a significant consideration for many, particularly for older adults.
According to nutrition experts, this is an important reminder, as recent research suggests that “dietary protein restriction promotes metabolic health, healthspan, and lifespan.”
A review paper published in Cell Press Blue outlines several biological processes through which a protein-restricted diet could enhance longevity. However, experts find these claims unconvincing, warning that such a diet could pose serious health risks to older adults, sedentary individuals, and those using GLP-1 weight loss medications.
Stuart Phillips, a kinesiology professor and expert on skeletal muscle health at McMaster University, criticized the study as “a beautiful mouse story, sold as human advice” on social media. He noted that for those over 65, particularly the very elderly, low protein intake is associated with negative outcomes like increased frailty, more frequent falls, and higher mortality rates.
The paper critiqued by Phillips involved authors from the University of Wisconsin-Madison’s department of medicine. They reviewed 350 previously published studies to provide “a comprehensive overview of current knowledge regarding the benefits of [protein restriction] and amino acid restriction for healthy aging, and highlights the therapeutic potential of interventions based on these diets to promote healthspan and longevity.”
Much of the research the authors referenced involved animal studies, which Phillips explained to STAT cannot be directly applied to human longevity. “The authors acknowledge that the effect of protein restriction on human lifespan is unknown. That is the central limitation,” he stated.
The authors describe “protein restriction” as a strong geroprotective strategy that reduces total dietary protein intake while still fulfilling nutritional requirements. However, experts argue that this is difficult to interpret within the context of human nutritional needs, which vary widely across different stages of life.
The latest Dietary Guidelines for Americans, issued jointly by federal health and agriculture departments in early 2026, suggest 1.2 to 1.6 grams of protein per kilogram of body weight. Most Americans are reportedly meeting this higher range, according to Donald Layman, a professor emeritus of nutritional sciences at the University of Illinois Urbana-Champaign, who contributed to setting these guidelines.
The Recommended Dietary Allowance (RDA) established by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine, recommends 0.8 grams of protein per kilogram of body weight. The RDA is set two standard deviations above the physiological need, indicating that the true minimum requirement is lower. Nonetheless, Phillips pointed out that older adults might need more protein than the RDA suggests.
Stacy Pelekhaty, a registered dietitian and senior clinical nutrition specialist at the University of Maryland Medical Center, observes that many patients begin focusing on longevity in midlife. At that stage, Pelekhaty noted, patients often live with more chronic injuries or illnesses, suggesting they might require higher protein intake.
As people age, the body’s ability to synthesize protein decreases alongside metabolism, leading to an increased need for dietary protein to maintain lean muscle, according to William Evans, a researcher in protein and aging and an adjunct professor of human nutrition at the University of California, Berkeley. Evans expressed skepticism regarding the purported benefits of a protein-restricted diet for older adults.
Evans also warned against equating maximal lifespan with a healthy lifespan. “Longevity doesn’t necessarily mean better care for geriatric patients,” he noted, emphasizing the importance of questions like “How do we keep older adults out of nursing homes?” and “How do we help them live a functional, independent life?”
Katie Dodd, who hosts the podcast “Geriatric Dietitian,” dedicates her clinical practice to enhancing the health and wellness of older adults. She referenced the PROT-AGE study initiated by the European Geriatric Medicine Society, which provides evidence-based recommendations for dietary protein intake in older people. It suggests 1-1.2 grams of protein per kilogram of body weight for older adults, with higher intake advised for those who exercise regularly.
“Healthy aging isn’t just about living longer. It’s about maintaining the strength and function to enjoy those extra years,” Dodd said, cautioning that reducing protein intake could accelerate muscle loss and threaten an individual’s independence.
In a press release, the authors of the Cell Press Blue paper suggested that sedentary individuals in the U.S. probably consume too much protein and might benefit from a protein-restricted diet. However, several experts expressed concern about this claim, as the authors did not specify the recommended protein amount for this group.
According to Evans, sedentary individuals still need sufficient protein to maintain lean tissue, and he believes the RDA of 0.8 grams per kilogram of body weight is adequate. Exercise supports the maintenance of lean tissue, so reducing protein intake in sedentary individuals could accelerate muscle loss over time.
Pelekhaty, the clinical nutrition specialist, pointed out that if sedentary individuals reduce protein intake without cutting overall calories, other macronutrients will replace it. Increasing carbohydrate intake, for instance, could raise the risk of chronic metabolic conditions affecting longevity and quality of life.
For those with a sedentary lifestyle on GLP-1 medications for weight loss, the risks are heightened, according to Pelekhaty. GLP-1 medications are linked to muscle mass loss and decreased metabolic rate, making adequate protein intake and physical activity crucial for maintaining lean tissue. The satiety from protein-rich meals paired with GLP-1 medications can prolong the feeling of fullness, complicating adequate protein consumption.
Experts also stressed the importance of considering the types of protein consumed. Some suggest that plant-based proteins may lower the risk of diabetes and heart disease due to their lower saturated fat content compared to animal products.
Phillips emphasized that the authors of the review paper and others researching premature mortality seem to advocate for a “more beans and less bacon” approach rather than a broad protein restriction. “A mixture of minimally processed plant and animal foods is very different from simply adding protein bars, powders, and ‘protein-fortified’ snack foods to an otherwise poor diet,” he said.
Dodd emphasized that protein targets should be tailored to an individual’s age, health status, muscle mass, kidney function, activity level, and overall goals. Experts concurred that maintaining functional health is more crucial than merely aiming for longevity.
Layman from Illinois remarked, “I think it’s far better to be an active 90-year-old than being a vegetable at 100.”
