Rethinking protein: Less may be more for healthy aging, study finds

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A woman shops for chicken at a supermarket in Santa Monica, California, on September 13, 2022. (Photo by Apu GOMES / AFP) (Photo by APU GOMES/AFP via Getty Images)

A new study pushes back on the notion that higher amounts of protein help stave off the ravages of aging. The research also comes as shoppers embrace increasing their protein intake and food makers respond by packing protein into more and more products.

The backstory:

For years now, grocery store shelves have been packed with protein-packed items ranging from soda to cereal and from popcorn to Pop-Tarts. There are even brands of protein-infused bottled water.

Earlier this year, the U.S. Department of Agriculture and the Department of Health and Human Services rolled out new dietary guidelines that put protein front-and-center and increased the recommended intake to 1.2–1.6 grams of protein per kilogram of body weight every day.

Big picture view:

The researchers behind the new study, which was published in the journal Cell Press Blue, also acknowledged that recommendations to increase protein during aging are widespread. They also referenced a 2025 report that found more than 6 in 10 people had increased their protein intake in the previous year, a notable jump from 2019 when that number stood at just under half.

However, they contend that more and more evidence is showing that restricting protein intake has proven benefits for metabolic health, healthspan, and lifespan across diverse organisms.

What they're saying:

"As protein-fortified foods flood grocery store shelves and older adults are urged to increase protein intake, the need to understand how dietary protein impacts aging is more important than ever," the study’s authors, Bailey A. Knopf and Dudley W. Lamming, wrote, adding elsewhere that "accumulating evidence challenges the idea that higher protein intake is beneficial."

Dig deeper:

The study notes early on that cutting calories has been a proven way to fight aging for nearly a century now, but points out that, for many people, watching what they eat can be too big of an ask. Instead, the researchers turned to protein restriction (PR), and a low-protein diet.

Knopf and Lamming explain that high-protein diets will activate the molecule mTORC1 in the body, forcing cells into a continuous growth mode and preventing them from doing the cleanup processes that improve metabolic health. The metabolic benefits, they continued, were found in limiting two specific amino acids–methionine and branched-chain amino acids (BCAAs)—as opposed to cutting all types of protein.

Knopf and Lamming’s summary also listed studies that linked high-protein diets with an increased risk of diabetes, cancer, and mortality, as well as of dying from a cardiovascular event. They also claim National Health and Nutrition Examination Survey data showed eating more protein has a positive correlation with a greater risk of mortality or being diagnosed with an age-associated disease, such as diabetes.

The authors returned to a 2016 report where subjects who ate a low-protein diet for 43 days lost weight and fat mass, while reducing fasting blood glucose. All of that happened despite actually eating more calories. They also cited several studies where protein was restricted for those living with diabetes where participants saw multiple positive effects.

Knopf and Lamming juxtaposed that with a recent study involving a high-protein, low-carbohydrate diet that they say may not have been as effective as a moderate-protein diet in terms of lowering blood glucose, improving glucose tolerance, and promoting prediabetes remission.

What you can do:

Unfortunately, everyone cutting their protein consumption indiscriminately does not appear to be an easy fix either, according to the authors’ findings.

Older adults, for example, are often told to up their protein intake and exercise to battle sarcopenia and frailty. Knopf and Lamming acknowledge the differing, sometimes contradictory, needs and suggest cycling periods of low protein consumption to mitigate concerns of nutrient signaling and increase cellular cleanup.

The amount of exercise they end up doing weighs in here as well, because it affects how the body will process the proteins. Most importantly, the authors encourage moving away from blanket recommendations and toward individual ones that include factors like age, sarcopenia risk, and activity levels.

The Source: Information for this article was taken from Cell Press Blue. This story was reported from Orlando.

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