Dudley Lamming of the University of Wisconsin-Madison says aging and protein intake research now points in a different direction for many sedentary adults: less protein may improve health and, in some cases, extend lifespan. The review, published July 31 in Cell Press Blue and covering over 350 papers, ties protein restriction to slower aging through metabolism, nutrient signaling, lower cellular damage and healthier cell function.
Lamming said many sedentary people are likely eating more protein than they need. “It’s absolutely crystal clear that there are benefits of protein to muscle growth and exercise response of active individuals. But because most people are relatively sedentary, many people are likely consuming more protein than they actually need, which probably has negative health consequences.”
Cell Press Blue review
The review does not rest on one experiment. It synthesizes decades of work showing that eating less calories can extend lifespan in many organisms, and that eating less protein can also extend lifespan in flies and rodents without lowering calorie intake. In humans, several recent clinical trials found that reducing protein intake lowered weight and fat mass and improved fasting blood sugar even when protein-restricted people tended to eat more calories.
The authors also point to FGF21, which rises when protein intake is low. In mice, higher FGF21 levels were linked with longer life, and the benefit was stronger in male mice than female mice. The same pattern appears in humans: eating less protein raises FGF21 there as well.
US protein guidance
The review lands as US authorities have already moved in the other direction for daily targets, updating dietary guidelines this year to recommend 1.2–1.6 grams of protein per kilogram of body weight, or 0.5–0.7 grams per pound. The new recommendation is nearly double the previous one, a shift that places the review’s conclusions beside a much higher public target.
That is where the complication sits. Some studies found that eating more protein could promote weight loss and reduce age-related muscle loss in older adults when paired with exercise. The review says methionine, isoleucine and valine appear to drive many of protein’s effects, and that too much of those amino acids could trigger biological processes that promote growth and raise the risk of obesity, inflammation and other age-related diseases.
Dudley Lamming
Lamming said the amount of protein sedentary people are eating today may have negative health consequences at the population level. “These studies show that the amount of protein sedentary people are eating today may have negative health consequences, at least at the population level,” he said.
For sedentary adults, the practical reading is narrower than the headline: the review supports rethinking very high protein intake, while the human trial data still show benefits from lower protein in some settings and from higher protein when exercise is part of the plan. The article leaves the balance between those two uses of protein as the live question for everyday diets.
