Eating More Protein May Not Always Be Better: Study Finds Lesser Protein Intake Might Slow Down Ageing

Protein has become a popular part of modern diets, with everything from breakfast cereals and snacks to drinks being marketed as high-protein options. However, a major scientific review suggests that consuming less protein may have potential benefits for metabolic health and healthy ageing, challenging the belief that more protein is always better.

The review published in the journal Cell Press Blue, which examined more than 350 scientific papers, found that reducing protein intake may influence biological processes linked to ageing, improve metabolism and potentially support a longer lifespan. However, researchers caution that protein requirements vary according to a person's age, health and physical activity levels.

How Could Eating Less Protein Affect Ageing?

Scientists have been studying how dietary changes influence lifespan and age-related diseases. While calorie restriction has been linked to longer lifespans in several organisms, eating fewer calories consistently can be difficult.

An alternative approach is to reduce protein intake without necessarily cutting down on total food or calories.

Experiments in flies and rodents have shown that limiting dietary protein can extend lifespan, even when overall calorie intake remains unchanged. Human studies have also reported improvements in certain metabolic markers, including fasting blood sugar, body weight and body fat, following reductions in protein intake.

However, these findings do not establish that eating less protein can extend human lifespan.

Also Read: How Much Protein Do You Need at Every Age? A Simple Guide to Meeting Your Daily Requirement

The Role of Hormones and Amino Acids

One possible explanation involves a hormone called fibroblast growth factor 21 (FGF21). Its levels increase when protein intake is restricted. The hormone helps regulate energy use and may support blood sugar control while reducing inflammation.

Animal studies have linked higher FGF21 levels to longer lifespans. Although researchers have also observed an increase in this hormone in humans following protein restriction, it remains unclear whether this produces the same longevity benefits.

The review also highlights three amino acids- methionine, isoleucine and valine, which may influence ageing-related processes. Excessive intake of these amino acids may activate biological pathways associated with growth and metabolism. Prolonged activation of some of these pathways could contribute to inflammation and metabolic problems.

Should You Reduce Your Protein Intake?

Not necessarily. Protein is essential for muscle growth, tissue repair and several important bodily functions. Consuming adequate amounts becomes particularly important for older adults, who may be at risk of age-related muscle loss, weakness and reduced mobility.

Pregnant women also need additional protein to support foetal development. People who exercise regularly may require more protein to help their muscles recover and adapt to physical activity.

The researchers suggest that sedentary adults may not benefit from adding excessive amounts of protein to their diets, particularly when their daily activity levels are low.

Also Read: Can Eating More Protein Help You Lose Belly Fat?

Why Protein Needs Should Be Personalised

The findings highlight the importance of looking beyond popular high-protein diet trends. A person's protein requirements depend on factors such as age, health, pregnancy status and exercise habits.

Rather than cutting protein drastically, people should focus on consuming an appropriate amount through a balanced diet. The study does not establish a universal low-protein diet for slowing ageing, and more human research is needed to understand its long-term effects.

The key takeaway is that eating more protein is not automatically better. Getting the right amount for your body's needs may matter more than simply increasing your intake.