INDIANAPOLIS, Ind. (WOWO) — A new scientific review suggests that reducing protein intake, rather than cutting calories, may offer some metabolic benefits for sedentary adults looking to support healthier aging.
Researchers reviewed more than 350 studies and found that lower protein consumption was associated with changes in metabolism, reduced inflammation, improved nutrient signaling and better cellular maintenance.
The review, published in Cell Press Blue, examined how protein restriction may influence biological processes connected to aging.
Previous research has shown that reducing overall calorie intake can improve lifespan and lower the risk of some age-related diseases, but experts say strict calorie-restricted diets can be difficult for many people to maintain.
Researchers behind the review say adjusting protein intake may provide another possible approach, although they stress the findings do not mean people should eliminate protein from their diets.
Much of the research focused on fibroblast growth factor 21, or FGF21, a metabolic hormone that increases when protein intake is restricted. Studies in animals have shown that higher FGF21 activity may improve energy use, reduce inflammation, support blood sugar control and potentially extend lifespan.
Researchers also examined three amino acids found in protein — methionine, isoleucine and valine — which play important roles in the body but may influence aging-related pathways under certain conditions.
Scientists say that for people who are physically inactive, consistently high levels of these amino acids may keep growth-related processes active in ways that could contribute over time to cellular stress, inflammation and weight gain.
Dudley Lamming, a researcher at the University of Wisconsin-Madison and corresponding author of the review, said protein remains essential for people who exercise regularly.
“It’s absolutely crystal-clear that there are benefits of protein for muscle growth and exercise response of active individuals,” Lamming said.
However, he added that because many people are relatively sedentary, some may consume more protein than their bodies need.
The researchers noted that the review has limitations. Because it analyzed existing studies rather than conducting a new clinical trial, it can identify patterns but cannot prove that reducing protein directly extends human lifespan.
Long-term human studies are still needed to determine whether the metabolic effects observed in research translate into longer lives or lower rates of chronic disease.
Experts also emphasize that protein needs vary from person to person.
Older adults, pregnant women and athletes may require higher protein intake because protein helps support muscle maintenance, growth and repair. Physical activity also changes how the body uses dietary amino acids.
For active individuals, protein remains an important part of building and preserving muscle. For people with lower activity levels, researchers say the findings suggest that nutrition recommendations may need to be more personalized rather than applying the same protein target to everyone.
The review’s authors say the goal is not to promote extremely low-protein diets, but to encourage a closer look at how protein intake, physical activity and age interact when considering long-term health.
