A major scientific review is challenging the widely held assumption that more protein is always better for health, suggesting instead that eating less protein, or fewer of certain amino acids, may activate biological processes linked to healthier aging for many adults who already consume enough.

The review, led by pathologist and biomedical researcher Dudley Lamming, was published in the journal Cell Press Blue and examined more than 350 studies involving humans, mice, insects, yeast and other organisms. The analysis found that reducing protein intake, or the intake of specific amino acids that make up dietary protein, may trigger body processes tied to healthier aging and improved metabolism, the process through which the body converts food and drinks into usable energy.

The findings arrive amid a cultural moment in which protein has become an increasingly ubiquitous marketing feature across the food industry. Protein is now added to lattes, cereal, chips, ramen and numerous other products that were never traditionally marketed as protein sources, reinforcing a broad public message that more protein consistently equates to better health. A 2025 survey by the International Food Information Council found that 70% of U.S. adults said they actively try to eat protein, with high-protein diets ranking as the most popular diet type in the United States for the third consecutive year. Many of those surveyed, however, reported that they did not actually know how much protein they needed.

Protein plays an essential role in building muscle, repairing tissue and supporting the body’s recovery processes, but individual protein needs vary considerably based on age, health status, body size and activity level. The general recommended daily allowance for a healthy adult is 0.8 grams of protein per kilogram of body weight, or roughly 0.36 grams per pound, meaning a person weighing 140 pounds would need approximately 51 grams of protein daily under that standard guideline.

Many Americans already consume protein well above that baseline recommendation. A typical meal often contains 20 to 30 grams of protein, frequently sourced from a 3- to 6-ounce serving of meat, chicken or fish. An analysis of national health data found that adults who met standard exercise guidelines consumed an average of about 82 grams of protein daily, while adults who did not meet those exercise guidelines still consumed roughly 79 grams per day on average, indicating that protein intake levels among American adults, whether physically active or not, generally exceed the baseline recommended amount by a wide margin.

Lamming, who studies aging at the University of Wisconsin-Madison School of Medicine and Public Health, suggested that sedentary individuals in particular may not need to continue increasing their protein intake beyond the standard guideline. “It’s probably safe to say that for sedentary individuals, maybe [follow] the original [recommended daily amount of] 0.8 grams per kilogram,” Lamming said. He clarified that this finding does not mean inactive adults need to immediately cut their current protein intake, only that they may not need to keep adding more. Lamming noted that for sedentary individuals specifically, simply increasing physical activity may provide greater health benefits than further increasing protein consumption alone.

The review examined how reduced protein intake affects several underlying biological processes tied to aging, including the activity of a hormone called FGF21. “There’s an increase in a hormone called FGF21 that promotes energy expenditure [when protein intake is reduced],” Lamming said. “It essentially increases thermogenesis in your adipose tissue, so you don’t just store fat, but actually burn it as fuel.” That mechanism may help explain why some studies have linked lower-protein diets to reduced body fat, improved blood sugar control and generally healthier metabolic function. Lamming’s review also found that reduced protein intake may influence cellular signaling processes that determine when cells grow, repair damage or recycle deteriorating internal components, functions believed to play a role in the broader aging process.

Lamming emphasized that protein restriction as described in the review is distinct from protein deficiency, and that the research is not suggesting people deprive their bodies of an essential nutrient. Instead, the findings raise the possibility that avoiding unnecessary excess protein intake, beyond what an individual’s body actually requires, could offer benefits for people who are already meeting their nutritional needs.

The review also emphasized that appropriate protein needs vary significantly from person to person, and that certain populations likely require more protein rather than less. Active adults, pregnant individuals, older adults, and people recovering from illness, injury or surgery may all have elevated protein needs compared with the general population. People actively working to lose weight may also need adequate protein intake specifically to help preserve muscle mass as they lose overall body fat. Older adults face particular considerations given the natural, age-related muscle loss known as sarcopenia; adequate protein intake combined with regular strength training exercise may help slow that process. People with kidney disease, liver disease or other underlying health conditions may require individualized dietary guidance that differs from general population recommendations.

The review’s authors acknowledged several limitations in the underlying research. The studies included in the analysis used varying diets, differing protein amounts and inconsistent study durations, and many of the studies were conducted in animals or other non-human organisms, meaning the results may not fully translate to human physiology. Given the individualized nature of protein needs and the potential health implications of significant dietary changes, anyone considering a major adjustment to their protein intake, particularly people with existing health conditions, older adults or those recovering from illness or injury, is encouraged to consult a doctor or registered dietitian before making changes, rather than relying solely on general research findings to guide personal dietary decisions.