A comprehensive scientific review has found that reducing protein intake may support healthier aging, improved metabolism, and reduced inflammation in adults who already consume adequate protein levels. The review, published in Cell Press Blue, analyzed more than 350 studies involving humans, mice, insects, and other organisms, challenging the prevailing trend of high-protein diets.
Key findings from the review include:
- Lower protein intake may activate processes linked to healthier aging, including improved blood sugar control and reduced inflammation.
- A hormone called fibroblast growth factor 21 (FGF21), which increases with reduced protein consumption, is believed to enhance energy expenditure and metabolic health.
- Clinical trials in humans have shown that protein restriction can aid weight loss and stabilize blood sugar levels, even when total calorie intake remains unchanged.
The review was led by Dudley Lamming, a pathologist and biomedical researcher at the University of Wisconsin–Madison. While the findings suggest potential benefits for protein reduction in certain populations, experts caution that much of the evidence stems from animal studies, leaving the direct applicability to humans uncertain.
How much protein do adults need?
Protein requirements vary based on age, health, body size, and activity level. The Recommended Dietary Allowance (RDA) for healthy adults is 0.8 grams of protein per kilogram of body weight, or about 0.36 grams per pound. For example, a 70 kg (154 lb) adult would need approximately 56 grams of protein daily. However, the review emphasizes that exceeding these recommendations may not provide additional benefits for individuals already meeting their protein needs.
The rise of protein-enriched products
The protein trend has led to the proliferation of protein-fortified foods, including lattes, cereals, chips, and ramen. A 2025 survey by the International Food Information Council found that 70% of U.S. adults attempt to increase protein intake, with high-protein diets remaining the most popular dietary approach for the third consecutive year. Despite this trend, many people remain unaware of their actual protein requirements.
Potential mechanisms and limitations
The review highlights several biological pathways through which reduced protein intake may confer health benefits. One key factor is the hormone FGF21, which rises in response to lower protein consumption and is associated with improved metabolic function. However, the authors note that most evidence comes from animal studies, and human trials are needed to confirm these effects.
Expert perspectives
While protein is essential for muscle repair, tissue maintenance, and overall health, the review suggests that moderation may be key for long-term well-being. Some researchers argue that excessive protein intake—particularly from processed sources—could contribute to metabolic stress over time. Others emphasize that protein needs are highly individualized and that blanket recommendations may not apply universally.
The findings add to a growing body of research exploring dietary strategies for longevity and chronic disease prevention. Future studies are expected to further clarify the optimal protein intake for different populations, including older adults and those with metabolic conditions.