Protein is everywhere right now. It’s in cereal, coffee, and even bottled water. Companies keep adding it because shoppers want it. However, a recent scientific review presents a contrasting perspective. It says eating less protein might actually be better for long-term health. In some cases, it might even help people live longer.
The review looked at more than 350 studies. It focused on protein restriction and ageing. The lead author is Dudley Lamming, a researcher at the University of Wisconsin-Madison. He and his team wanted to understand how cutting back on protein affects the body over time.
Lamming is clear about one thing. Protein does help muscles grow. It also helps people recover from exercise. That part isn’t in question. The problem is different. Most people today don’t move around much. They sit at desks. They drive instead of walk. Because of this situation, many people eat more protein than their bodies actually need. That excess protein may cause health problems over time.
The Calorie Connection
Scientists have known for decades that eating fewer calories can extend life. This effect has been shown in many animals. It also lowers the risk of diseases linked to ageing, like cancer. But sticking to a low-calorie diet is challenging. Most people can’t do it long-term.
Protein restriction seems to work differently. Studies on flies and rodents found that cutting protein extends lifespan, even without cutting calories. Human trials point the same way. People who ate less protein lost weight and body fat. Their blood sugar control also improved. This happened even though they often ate more calories overall to make up for the lower protein.
A Mixed Picture
Not all research points in one direction, though. Some studies show the opposite effect. Eating more protein, combined with exercise, can help older adults lose weight and hold onto muscle. This evidence pushed U.S. health officials to update their guidelines this year. The new advice recommends more protein per day than before, almost double the old target.
So Lamming’s team set out to make sense of this contradiction. Why does more protein seem harmful in some studies but beneficial in others?
What’s Happening Inside the Body
The review points to several biological mechanisms. Eating less protein changes how the body handles nutrients. It reduces cell damage. It also helps preserve healthy cell function over time.
One major factor is a hormone called FGF21. Levels of this hormone rise when protein intake drops. FGF21 boosts the body’s energy use. It improves blood sugar control. It also lowers inflammation. In mouse studies, animals with higher FGF21 levels lived longer. This effect was stronger in male mice than female mice. The same hormone rises in humans on lower-protein diets too.
Certain amino acids also play a role. These are the building blocks of protein. Three stand out: methionine, isoleucine, and valine. Eating too much of these may trigger growth-related processes in the body. Over time, this can raise the risk of obesity and inflammation and other diseases tied to ageing.
Why Athletes Seem Fine
Here’s the puzzle piece that ties it together. Athletes often eat huge amounts of protein. Yet they don’t tend to develop the same metabolic problems. Lamming thinks exercise is the key. Physical activity may direct that extra protein toward building muscle. That process seems to protect the body from protein’s downsides.
Not a One-Size-Fits-All Answer
Lamming isn’t saying protein is bad. Some groups need more of it. Pregnant women are one example. Certain older adults are another example. But for most sedentary adults, protein-fortified snacks and drinks may not deliver the benefits people expect.
His main takeaway is about personalization. Protein needs shouldn’t be based on age alone. Activity level matters just as much. A runner and a desk worker of the same age may need very different amounts of protein to stay healthy.
