MADISON, WI — Protein has been sold as the answer to nearly every food question, from breakfast drinks to snack bars. But a new scientific review argues that more is not automatically better for every adult, and in some cases, slightly less protein may be the smarter path.
The analysis looked at more than 350 studies across humans and other organisms, and it focused on how protein intake may influence aging, metabolism, and body processes tied to energy use.
1. The review challenges the idea that more protein always helps
The paper was led by pathologist and biomedical researcher Dudley Lamming and published in Cell Press Blue. It pulled together research from humans, mice, insects, yeast and other organisms to test a simple question: do adults really need to keep pushing protein higher?
The answer from this review is more complicated than the marketing around protein-heavy foods suggests. For adults who already meet their needs, the study says extra protein may offer little added benefit, while lower intake could support healthier aging-related pathways.
2. Many Americans are already eating plenty of protein
A 2025 survey from the International Food Information Council found that 70% of U.S. adults said they try to eat protein, and high-protein diets were the most popular eating style for the third year in a row. Even so, many people said they did not know how much protein they actually need.
The review points out that a typical meal can already deliver 20 to 30 grams of protein, often from a 3- to 6-ounce serving of meat, chicken, or fish. National health data also found adults who met exercise guidelines averaged about 82 grams a day, while those who did not still averaged about 79 grams.
3. The standard target for a healthy adult is lower than many people think
For healthy adults, the recommended daily amount is 0.8 grams of protein per kilogram of body weight, or about 0.36 grams per pound. That works out to roughly 51 grams a day for someone who weighs 140 pounds.
Lamming said that for sedentary people, it is probably safe to stick close to that original recommendation. The point is not that inactive adults should suddenly slash protein, but that many may not need to keep adding more to already adequate diets.
4. Less protein may affect hormones linked to energy burning
One of the review’s most interesting findings involves a hormone called FGF21. Lamming said lower protein intake appears to increase FGF21, which can raise energy expenditure and thermogenesis in adipose tissue, the process that helps fat tissue burn fuel instead of just storing it.
That could help explain why some studies connect lower-protein diets with less body fat, improved blood sugar control, and a healthier metabolism. The review suggests these effects may be part of the body’s broader response to reducing protein or specific amino acids.
5. Restriction is not the same as deficiency
The researchers were careful to draw a line between lowering protein and becoming protein deficient. Protein is still essential for building muscle, repairing tissue, and helping the body recover from daily wear and tear.
What the review questions is the push to consume extra protein when the body may already be getting enough. The takeaway is not to deprive yourself of an essential nutrient, but to avoid unnecessary excess if your diet already covers your needs.
6. Some people still need more protein than others
Protein needs depend on age, health, body size, and activity level. Active adults, pregnant people, older adults, and people recovering from illness, injury, or surgery may need more. People trying to lose weight may also need enough protein to help preserve muscle as they shed body fat.
Older adults deserve special attention because aging can lead to sarcopenia, a gradual loss of muscle and strength. The review notes that enough protein, combined with strength exercise, may help slow that process. People with kidney disease, liver disease, or other medical conditions should get individualized advice.
7. Scientists say the evidence is promising but not settled
The review has limits because the studies it examined used different diets, different protein levels, and different time spans. Many of them were done in animals or other nonhuman organisms, which means the findings may not translate neatly to people.
Even so, the message is clear enough for healthy adults already eating enough: protein remains important, but it may not need to appear in every meal, snack, and drink. Before adding another high-protein product to the cart, the more useful question may be how much protein the body actually needs.
Wrap-up
For many adults, this review does not argue against protein. It argues against reflexively chasing more of it. The most practical next step, especially for anyone considering a big dietary shift, is to talk with a doctor or registered dietitian about personal needs.
