SUMMARYA scientific review led by Dudley Lamming examined more than 350 studies across humans and other organisms and found that lowering protein intake or certain amino acids may activate biological pathways linked to healthier aging and metabolism. The research points to changes in the hormone FGF21, increased energy expenditure, and improved fat burning, blood sugar control, and body composition in some settings. The findings suggest that people who already consume enough protein may not benefit from eating more.

"A major scientific review is challenging the idea that more protein is always better," reports ABC News:

The review, led by pathologist and biomedical researcher Dudley Lamming and published in the journal Cell Press Blue, examined more than 350 studies involving humans, mice, insects, yeast, and other organisms. The review found that eating less protein, or less of certain amino acids that make up protein, may turn on body processes linked to healthier aging, as well as metabolism, the process by which the body turns food and drinks into energy...

For adults who already get enough, eating more protein may offer little benefit, while some research suggests that eating less protein could support healthier aging... Lamming reviewed the effect of reducing protein in many body processes. One of the processes involves 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." This may help explain why some studies connect lower-protein diets with less body fat, better blood sugar control and a healthier metabolism. Eating less protein may also affect signals that tell cells when to grow, repair damage or recycle old cell parts. These jobs may play a role in aging.

However, protein restriction is not the same as protein deficiency. The goal is not to deprive the body of an essential nutrient. Instead, the research raises the possibility that avoiding unnecessary excess could benefit some people who already consume enough... Before reaching for another high-protein product, a better question may be: How much protein does my body actually need?