Is Eating Too Much Protein Bad for Longevity?

Social media can make you believe that higher protein intake can solve many health issues. What it doesn't say is that overconsuming protein, especially from animal sources, may result in a shorter lifespan.

As many as 61% of Americans increased their protein intake in 2024, up from 48% who did so in 2019. The trend may be at least partly explained by the ongoing protein craze, often driven by wellness and nutrition influencers who promote higher protein intake for weight loss and other proposed health benefits.

At the same time, there is an increasing interest in low-carbohydrate diets like ketogenic or carnivore, which nutrition experts warn against following.

Protein is an essential nutrient that plays an important role in repairing cells and making new ones. It is also necessary for growth and development in children, teens, and pregnant women.

However, there can be too much of a good thing. Evidence suggests that consuming excessive protein may have negative effects on health and longevity.

How much protein do we need?

The Dietary Guidelines for Americans recommend that adults get 10% to 35% of their total calories from protein, such as meat, poultry, seafood, and legumes. In a standard 2,000-calorie diet, that would be between 200 and 700 kcal.

Another way to determine protein needs is to consider body weight (BW). Adults need about 0.8 g of protein per kg BW, the amount that increases with physical activity levels.

Those who engage in moderate physical activity may need 1.3 g of protein per kg BW, while those with intense physical activity should consume 1.6 g of protein per kg BW.

Chronic intake of more than 2 g of protein per kg BW should be avoided, as it may result in digestive, renal, and vascular abnormalities.

The aggressive marketing of high-protein diets and products continues despite data indicating that Americans consume too much protein and don't get enough fiber, which is absent in many high-protein foods.

Why is too much protein bad for longevity?

Excessive protein intake may have negative health effects resulting in decreased lifespan, but they depend greatly on the source of protein, not just the total quantity, according to Avery Zenker, RD. For example, eating too much protein from animal sources like red meat and processed meat could lead to earlier death.

High-protein diets may result in excessive calorie intake, contributing to obesity, Zenker says. Extreme obesity is estimated to shorten lifespan by as much as 14 years.

Daniel Atkinson, MD, says consuming too much protein can raise blood pressure and 'bad' cholesterol levels, which in turn may raise the risk of heart attack and stroke. He cites a study suggesting that adults aged 50 to 65 who consumed between 10 and 20% of their calories from protein were at higher risk of diabetes and cancer-related mortality.

People who eat most animal protein have higher levels of insulin-like growth factor 1 (IGF-1), which is associated with higher mortality risk.

Some studies show that a high intake of animal protein, particularly red meat containing high levels of amino acids methionine and BCAAs, may be related to the promotion of age-related diseases.

But what about increasing protein intake when you are already facing health issues?

A 2025 study involving 3,397 intensive care unit patients tested whether high-protein enteral feeding improved patient outcomes compared to lower protein. No differences were found in survival, nor did high protein result in faster recovery, shorter ICU or hospital stays, ventilation time, or improved kidney outcomes.

Plant vs animal protein for longevity

Animals and plants are major protein sources, but they differ in their amino acid profiles and digestibility. A common argument against plant-based protein is that it isn't complete, meaning it lacks one or more of nine essential amino acids.

However, the combination of different plant-based foods can provide complete protein. So, are they equally beneficial for longevity?

A recent study evaluated dietary patterns and their association with healthy aging, including living to 70 years free of chronic diseases. It found that higher intakes of fruits, whole grains, vegetables, added unsaturated fats, nuts, legumes and low-fat dairy were associated with greater odds of healthy aging.

Among foods linked to lower odds of healthy aging were total meats as well as red and processed meats.

Higher animal protein intake in middle adulthood has been associated with a higher risk of early death, mainly driven by death from cardiovascular disease, according to a 2020 study. Such a link was mainly attributed to the consumption of meat and dairy.

Conversely, those who consumed more plant-based protein had lower odds of early death from all causes and cardiovascular disease.

In a 2024 study, higher plant protein intake was associated with a better probability of achieving healthy aging, defined by changes in functional impairments, self-reported health, mental health, and use of health services.

Zenker says associations showing benefits of plant protein could be explained by different nutrient components. Plant-based protein is free of cholesterol and contains little to no saturated fat, while animal protein tends to contain more saturated fat and cholesterol, depending on the type.

"Plant proteins also come packaged with other beneficial nutrients, including fiber, antioxidants, and phytonutrients," Zenker tells WellnessPulse.

However, not all animal protein is bad, according to Atkinson. When consumed in moderate quantities, red meat can provide essential nutrients like iron. Other animal proteins like salmon and tuna are high in omega-3, which are beneficial for heart health.

It's best to have a balance of both sources of protein and not neglect other macronutrients, such as healthy carbohydrates, fruits, and vegetables in your diet.

Daniel Atkinson, MD

Risks of low protein at older ages

While excessive protein may cause health issues, a low-protein diet may not benefit everyone, according to Atkinson.

"If you are over 66, a higher protein diet may reduce your cancer risk and improve your overall health. This could be due to its role in combating related muscle loss, maintaining strength and mobility, and enhancing brain and heart health," he says.

The verdict

Despite the ongoing protein craze on social media, most people don't need to increase their protein intake. In fact, consuming too much animal-based protein is associated with shorter lifespans and worse health later in adulthood. Nevertheless, moderate consumption of animal protein can provide important nutrients and vitamins.