Experts Warn Against Protein Restriction for Older Adults

A review published in Cell Press Blue claims that a protein-restricted diet could promote healthspan and lifespan by improving metabolic health through various biological mechanisms. However, many nutrition professionals find the evidence unconvincing. Stuart Phillips, a professor at McMaster University, remarked that the study provides a misrepresented view of what applies to humans, stating that low protein intake in older adults is linked to negative health outcomes, such as increased frailty and higher mortality rates.

The review's findings incorporated data from 350 research papers, mainly from animal studies, which Phillips argues cannot directly apply to human longevity. The authors concede that the effects of protein restriction on human lifespan remain unknown, deeming it a significant limitation.

The latest Dietary Guidelines for Americans, released by federal health and agriculture departments in early 2026, recommend an intake of 1.2 to 1.6 grams of protein per kilogram of body weight. This recommendation aligns with findings from Donald Layman, a professor emeritus at the University of Illinois, who noted that most Americans are meeting these higher needs. Additionally, the Recommended Dietary Allowance suggests 0.8 grams per kilogram, which Phillips believes may still underestimate the protein needs of older adults.

Stacy Pelekhaty, a registered dietitian, highlighted that individuals often increase their focus on longevity in middle age when they may start experiencing chronic health issues, indicating a greater need for protein. William Evans, a researcher at the University of California, Berkeley, expressed skepticism regarding the benefits of protein-restricted diets for older adults, emphasizing the importance of maintaining lean muscle mass as metabolism slows with age.

Katie Dodd, a clinical dietitian, noted that the PROT-AGE study recommends 1-1.2 grams of protein per kilogram for older adults, with higher intakes for those who exercise regularly. She stressed that healthy aging involves maintaining strength and function, which a reduction in protein could hinder.

Concerns also exist about claims that sedentary individuals might benefit from protein restriction. Evans argued that even those who are less active need sufficient protein for lean tissue maintenance, pointing out that adequate protein intake is essential to counter muscle loss associated with both sedentarism and GLP-1 medications.

Experts also emphasized that the quality of protein consumed matters. Phillips suggested that a diet focusing on a mix of minimally processed plant and animal proteins may be more beneficial than merely reducing total protein intake. Dodd added that protein requirements should be tailored to individual health status, muscle mass, activity level, and goals.

Overall, experts concur that functional health should take precedence over longevity, with Layman stating that being an active 90-year-old is preferable to living in a state of decline at 100.