A Cell Press Blue review published in July 2026 argues that many Americans eat more protein than they need. The paper, from researchers at the University of Wisconsin-Madison, drew on more than 350 previous studies.
Its central claim is that dietary protein restriction may improve metabolism and extend lifespan. Several nutrition and geriatric researchers have now pushed back, telling STAT News that broadly cutting protein carries real trade-offs and that the strongest evidence for benefit still comes from animals, not humans.
Where the caution comes from
Stuart Phillips, professor of kinesiology at McMaster University, told STAT News the review is "a beautiful mouse story, sold as human advice."
"In people over 65, and especially in the very old, low protein is linked to worse outcomes, not better ones," Phillips said, pointing to higher rates of frailty, falls and mortality.
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Dudley Lamming, the review's corresponding author at the University of Wisconsin-Madison, has acknowledged part of that gap himself. He told Medical Xpress that recommendations may need to account for physical activity, not just age.
"It's absolutely crystal clear that there are benefits of protein to muscle growth and exercise response of active individuals," Lamming said, adding that sedentary people appear to consume more protein than they actually need.
William Evans, adjunct professor of human nutrition at the University of California, Berkeley, told STAT News he is "very skeptical" of the proposed benefits of a protein-restricted diet for older adults, and that sedentary individuals still require enough protein to maintain lean tissue.
Donald Layman, professor emeritus of nutritional sciences at the University of Illinois Urbana-Champaign, put it more bluntly. "I think it's far better to be an active 90-year-old than being a vegetable at 100," he said.
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Concerns for older adults and GLP-1 users
Stacy Pelekhaty, senior clinical nutrition specialist at the University of Maryland Medical Center, sees a particular problem for people taking GLP-1 weight-loss drugs.
Those medications are already "associated with loss of muscle mass and decreased metabolic rate," she told STAT News. Cutting protein on top of that, she cautioned, can accelerate muscle loss.
Katie Dodd, a registered dietitian who hosts the Geriatric Dietitian podcast, framed the concern directly. "Healthy aging isn't just about living longer. It's about maintaining the strength and function to enjoy those extra years," she said. Reducing protein, she warned, could speed muscle loss and threaten a person's independence.
Muscle also does not preserve itself with diet alone. Adequate protein works best when combined with resistance work, and experts recommend building a strength routine, particularly after 40, to protect against sarcopenia, or age-related muscle loss.
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What the U.S. guidelines actually say
The direction of official advice is currently the opposite of restriction. The 2025-2030 Dietary Guidelines for Americans suggest 1.2 to 1.6 grams of protein per kilogram of body weight per day.
That is roughly 50 to 100 percent above the previous minimum recommendation of 0.8 grams per kilogram. Harvard's Nutrition Source has separately noted that the guidelines do not clearly distinguish which protein foods to prioritize, and that many Americans already exceed their needs.
For most people, the practical takeaway is not to slash protein in pursuit of a longer life. It is to eat enough to protect muscle and stay physically active. Anyone considering a major dietary shift should talk to a doctor or registered dietitian first.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.