Eating Too Much Protein? The New Study Shaking Up the Nutrition Trend | Dr. Itay Gal

A review of more than 350 studies, published in the journal Cell Press Blue, found that a moderate reduction in protein intake may improve metabolism and blood sugar balance. However, most evidence for lifespan extension comes from animal studies, and human studies have been mostly small and short-term. Experts warn that uncontrolled reduction could harm populations such as the elderly, children, and pregnant women.

A large-scale review published in late July in the scientific journal Cell Press Blue, conducted by researchers from the University of Wisconsin-Madison, examined more than 350 studies on the link between protein, amino acids, aging, body weight, blood sugar, and cell function. The studies were conducted on yeast, flies, worms, rodents, and humans. In some animal studies, protein reduction extended lifespan even without calorie reduction, improved insulin sensitivity, and reduced fat. However, the researchers emphasize that a fly or a mouse is not a human, and human studies mainly examined measures like weight and sugar, not lifespan or disease. In some human trials, participants who reduced protein lost weight and improved fasting sugar, sometimes even without reducing calories. The review also addresses amino acids such as methionine, isoleucine, and valine, whose high intake may activate growth pathways linked to obesity and inflammation. However, protein reduction is dangerous for the elderly, children, pregnant women, convalescents, and athletes. The researchers did not set an exact amount, and the recommendation depends on age, weight, activity, and kidney function. They call for long-term human studies.