Does eating a lot of protein cause the body to age faster?

Many people increase their intake of meat, eggs, milk or supplement with protein powder to aid weight loss, create a feeling of fullness and maintain muscle. However, a new review of research raises the question: whether a long-term high-protein diet can stimulate cell growth, thereby affecting the aging process.

Bailey A. Knopf and Dudley W. Lamming, University of Wisconsin–Madison, analyzed more than 350 studies in a review published in the journal Cell Press Blue in July. This work was performed on humans, animals, yeast and cell cultures. The results show that reducing the amount of protein or some essential amino acids such as methionine, isoleucine and valine can improve metabolism and prolong healthy life in many of the studied organisms.

How protein can impact aging

Protein provides amino acids, raw materials for the body to form muscles, hormones, enzymes and many other essential ingredients. The amount of amino acids in the body also affects how cells use nutrients for growth and recovery.

According to an overview by Knopf and Lamming, when protein intake is reduced to a reasonable level, without causing nutritional deficiency, mTORC1 activity can decrease. This is a system that helps cells recognize the amount of available nutrients and regulate their growth process. In experimental studies, this change helps cells increase the removal of damaged substances, while also improving blood sugar control, mitochondrial activity and some manifestations related to aging.

A low-protein diet can also increase FGF21, a hormone involved in energy regulation as well as sugar and fat metabolism. From the evidence compiled, the research team believes that protein restriction can impact the aging process in many ways, such as improving metabolism, regulating cell activity, supporting the removal of senescent cells and maintaining energy production function.

However, each amino acid can affect the body differently. Some animal experiments show that reducing methionine, isoleucine or valine yields a fraction of the changes similar to low-protein diets. Therefore, the impact of protein may depend on intake, amino acid type and food source, not just on total grams of protein per day.

Does eating less protein help you live longer?

The above article is not a new clinical trial. In particular, Knopf and Lamming synthesized results from many works with different methods to explain possible mechanisms related between protein intake and the aging process. Evidence for longevity comes mainly from animals and laboratory organisms. Meanwhile, human studies usually only take place over a short period of time and monitor metabolic changes.

For example, one trial had participants reduce their branched-chain amino acid intake by 75% over 7 days. The results showed that the concentration of these substances in the blood decreased, and the body responded better to insulin. In another 8-week study, restricting sulfur-containing amino acids increased FGF21 and reduced weight and leptin levels – a hormone involved in regulating hunger and energy. These changes may benefit metabolism, but it has not been shown that participants age more slowly or live longer.

Professor Paul Greenhaff, an expert in muscle metabolism at the University of Nottingham, told Science Media Center that mice and insects differ from humans in their metabolic rate and body changes as they age. Therefore, the above results help open up new research directions, but cannot be applied directly to humans.

Knopf and Lamming also said that it is not possible to determine which protein amount helps people live longer. The current results mainly suggest a different perspective on the trend of increasing protein, but there is not enough basis to recommend that people reduce protein to slow down aging.

How much protein is enough?

Healthy dietary guidelines updated by the World Health Organization in January 2026 state that protein accounts for about 10-15% of total daily energy, which is usually enough to meet the needs of adults. With a 2,000 kcal serving, this equates to about 50–75 g of protein. Needs may be higher in athletes, muscle builders and some specific groups.

This number should not apply to everyone. Age, activity level, total energy intake, pregnancy, underlying medical conditions and recovery all change needs. Older adults also face loss of muscle mass and strength, so protein deficiency can increase the risk of weakness, falls, and loss of self-care.

The 2022 European Society of Clinical Nutrition and Metabolism geriatric nutrition guidelines recommend that older people receive at least 1 g of protein per kg of body weight per day, adjusted for nutrition, exercise, disease and tolerance. Older healthy people are usually recommended around 1-1.2 g/kg/day; Needs may be higher when sick or malnourished.

Pregnant women, growing children, people with low energy intake, people recovering from injury or surgery, and the elderly who have eaten little should not limit themselves in protein or amino acids. People with kidney disease also need their protein intake to be individualized by their doctor or nutritionist, instead of increasing or decreasing according to trends.

Nutritional principles

For healthy adults who do not exercise intensely, the important thing is not to try to eat as much protein as possible but to build a balanced diet of protein, vegetables, whole grains and healthy fats. The World Health Organization (WHO) notes that consuming too much protein can increase the metabolic burden on the body, especially the kidneys.

The impact of protein on health depends on the food source. Beans, tofu, nuts and whole grains provide protein, fiber and many micronutrients. Fish, eggs, milk and lean meat are also sources of protein with high nutritional value. Meanwhile, if you mainly increase your protein intake with processed meat, your diet may contain more salt and saturated fat.

According to WHO, many adults can improve their diets by replacing a portion of red meat with plant-based protein sources. Therefore, you should not eliminate protein from your diet but need to eat enough according to your needs, choose a variety of food sources and do not abuse supplements to replace balanced meals.

New research results show that the relationship between protein and aging is more complex than the “more is better” concept. However, without long-term human trials, it is not possible to conclude that eating a lot of protein causes the body to age quickly or that eating less protein helps prolong life.

In addition to nutrition and exercise, proactively preventing infectious diseases also contributes to helping people live healthy lives in old age. A severe illness or prolonged hospital stay can cause older adults to lose physical strength, limit mobility, and have difficulty maintaining muscle mass.

In 2025, WHO emphasizes that adult vaccination contributes to healthy aging and improves quality of life. Each person should base on their age, underlying medical conditions, vaccination history and recommendations in their place of residence to discuss with medical staff and choose appropriate vaccines.