While some believe the current trend of “protein maxxing” could lead to longer and healthier lives, recent research indicates the contrary: lowering protein consumption might actually extend lifespan and save money.
This social media-driven protein maxxing phenomenon has aligned with an abundance of protein-enriched products on the market, from water to Starbucks drinks to Doritos. Many are buying these items to gain muscle, yet research shows most Americans already consume sufficient protein.
A new study released in Cell Press Blue on Friday reviews over 350 prior studies, revealing significant evidence that excessive protein may be detrimental.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
“On average, humans consume about 17 percent of their calories from protein,” according to Dudley Lamming, a professor at the University of Wisconsin–Madison and co-author of the paper.
Lamming notes that in previous studies, mice on a 20 percent protein diet, when given significantly less protein (5 to 8 percent), had increased lifespans.
The connection between high protein intake and reduced lifespan is partly due to essential amino acids. These are primarily obtained from dietary protein, as our bodies cannot produce them. Although necessary for growth and survival, Lamming’s research indicates they can be harmful in excess. In a July 24 paper in Nature Aging, he and colleagues showed that reducing the amino acid valine increased male mice’s median lifespan by 23 percent, or half a year. These mice also displayed fewer signs of aging and less fat tissue, with fewer cancers.
“Essential amino acids in protein are necessary,” says Steven Heymsfield, a professor at Louisiana State University not involved in the study or Lamming’s research. However, once muscle and organ needs are met, “any excess is just energy. If you consume excessive protein beyond your amino acid need, it’s converted to fat or used as calories. I see the heavy protein intake trend as just BS.”
Many studies link calorie restriction to longer life, but it’s challenging for people to implement. Lamming and others propose that protein restriction might offer similar benefits. Most longevity and protein-restriction studies use animal models like mice due to the difficulty of tracking a human’s diet over a lifetime. Despite differences, data from these studies can be relevant to humans, as both species need similar protein proportions and rely on nine essential amino acids.
“Mice are excellent models for human food because they eat similarly and use it for growth, reproduction, and maintenance,” says Lamming.
The studies reviewed varied in species and sex of mice and rats, but a low-protein diet was linked to lifespan increases of up to 53 percent, akin to a human living past 120 years from an expected 80 years.
Researchers attribute this longevity to the hormone FGF21. Protein restriction in humans or mice boosts FGF21 production, which, upon reaching the brain, triggers sympathetic signaling. This process stimulates white fat cells to produce more mitochondria, leading to fat being used as energy.
“Protein-restricted animals, and even humans, have been shown to have higher energy expenditure,” Lamming explains.
Reducing excess fat can decrease the risk of conditions like diabetes, heart disease, and some cancers.
Heymsfield mentions other advantages of protein restriction. Excess protein digestion produces urea in the liver, potentially leading to kidney problems. High-protein foods often contain saturated fats, which are linked to heart disease, drawing criticism toward meat-heavy diets like keto.
Determining the ideal protein intake for humans is complex. The U.S. Department of Agriculture recently updated its guidelines from 0.8 grams to 1.2 to 1.6 grams of protein per kilogram of body weight daily. (The update, presented by Secretary of Health Robert F. Kennedy, Jr., in January, has faced criticism from doctors who allege conflicts of interest in its development.) This higher protein recommendation contrasts with suggestions to reduce intake. Protein needs vary: pregnant individuals and those recovering from injury or engaging in intense physical activity may require more.
“For those who exercise, protein is likely beneficial and not harmful,” Lamming states. “However, for sedentary individuals, excessive protein may be detrimental.”
