More Isn't Always Better
For years, the message has seemed simple: eat more protein to build muscle, stay full, and age gracefully. Recent dietary guidelines even suggested nearly doubling the previous recommendation for some adults. However, a groundbreaking review of over 350
studies, published in the journal Cell Press Blue, is challenging this blanket advice. Researchers from the University of Wisconsin-Madison found that for many sedentary adults, eating less protein—not more—might actually promote better metabolic health and support healthier aging. The review suggests that because most people are relatively inactive, they are likely consuming more protein than their bodies need. This excess could have negative health consequences, while restricting protein appears to improve metabolism and reduce cellular damage in many organisms, including humans.
The Sedentary Versus Active Divide
The key distinction highlighted by the new review is activity level. The benefits of higher protein intake for muscle growth and exercise recovery are well-established and not in dispute. For physically active individuals, protein intakes of 1.4 to 2.0 grams per kilogram of body weight per day can improve how the body adapts to training. The caution is aimed at the majority of the population that is largely sedentary. For this group, the review suggests that lower protein intake may activate pathways linked to longevity and metabolic health. This happens partly by triggering a hormone called FGF21, which rises when protein intake falls and has been linked to improved glucose control and lower inflammation. The researchers emphasize that protein recommendations should be personalized, factoring in not just age but also how physically active a person is.
Why Age Complicates the Picture
While the review cautions sedentary people against overconsumption, it also acknowledges a critical paradox when it comes to older adults. After the age of 40 or 50, we naturally begin to lose muscle mass, a condition known as sarcopenia. To combat this, many experts recommend that older adults increase their protein intake to a range of 1.0 to 1.2 grams per kilogram of body weight, which is higher than the base recommendation for younger, sedentary adults. This increased need is partly due to "anabolic resistance," where the body becomes less efficient at using protein to build muscle. Some studies suggest older adults need almost double the protein per meal as younger adults to stimulate muscle protein synthesis effectively. However, the new review also notes that many older adults already consume too little protein due to reduced appetite or other issues, making protein restriction potentially harmful for them. This creates a complex situation where some older adults need more protein to preserve muscle, while others might benefit from less if they are sedentary and at risk of metabolic disease.
Finding Your Personal Protein Target
So, what does this all mean for you? The overarching message is the end of one-size-fits-all protein targets. The old standard of 0.8 grams per kilogram of body weight is now widely seen as the minimum to prevent deficiency, not what's optimal for health. Your ideal intake depends on a combination of factors. If you are very active, lifting weights, or doing endurance training, your needs are higher, likely in the 1.2 to 1.7 g/kg range, to support recovery and muscle maintenance. If you are an older adult, aiming for at least 1.0 to 1.2 g/kg is recommended to help fight off age-related muscle loss. But if you are a largely sedentary adult, the latest review suggests that mindlessly chasing high protein targets might not be the best strategy for long-term metabolic health. Rather than focusing on a single number, the goal is to match your intake to your lifestyle.
