Do humans need to eat animal protein to build muscle? Science has the answer

Nearly 90% of adults in the United States believe they must eat meat, dairy, or eggs to get enough protein. This finding comes from a poll of 2,203 people who were surveyed in January 2025, and it highlights the lingering confusion around animal protein and plant-based eating.

Women and Gen Z participants were most likely to push back against the idea that animal products are required for adequate nutrition.

Dr. Roxanne Becker, MBChB, DipIBLM, who is with the Physicians Committee for Responsible Medicine, notes that some consumers still struggle to see how plant foods can match traditional protein sources.

Can plant protein replace animal protein?

Consumers may worry about protein quality when moving away from animal foods. One key concern is about whether plant proteins are too low in essential amino acids.

Plant-based proteins are often linked with health perks such as high fiber and reduced levels of unhealthy fats.

They also contain a variety of vitamins and minerals that animal products may lack, but the question about adequate essential amino acids remains.

Plant protein vs. animal protein

“Plant protein has been shown in randomized controlled trials to be as effective as animal protein for building muscle when the amounts of protein are equal. And it is full of nutrients and fiber, unlike animal-based protein sources,” clarified Dr. Becker.

There is strong support from controlled trials for the benefits of plant-based eating. 

In one study, men who followed a plant-based dietary plan or an omnivorous plan experienced similar gains in muscle mass when the diet was paired with resistance training.

Similar protein amounts produced comparable results, regardless of the protein source. 

Plant protein supports better aging

Midlife nutrition habits can set the stage for quality of life decades later. An investigation led by researchers from Harvard T.H. Chan School of Public Health (HSPH) suggests that higher intake of plant protein in midlife may support healthy aging in women.

Participants in that study showed better physical and cognitive outcomes over the years when they relied on beans, nuts, and other plant-based staples.

The findings indicate that animal protein may have a few benefits for mobility, but plant protein aligns with improved overall well-being. 

Practical protein needs

The minimum daily requirement for an adult is 0.8 grams of protein per kilogram (0.01 ounces per pound) of body weight.

That’s about 56 grams for a 70-kilogram (2 ounces for a 155-pound) man and 46 grams for a 58-kilogram (1.6 ounces for a 128-pound) woman.

Those who exercise heavily may need up to 2 grams per kilogram (0.07 ounces per pound), especially if they’re doing strength training.

Keeping track of these figures can guide individuals toward balanced dietary choices that nourish muscle growth and support overall health.

Maintaining muscle with age

“As we age, it’s important to consume enough protein to maintain our muscle mass so we can avoid frailty. Plant protein sources, which contain no artery-clogging cholesterol and are low in saturated fat, should be the go-to,” said Dr. Becker.

Older adults might lose muscle mass over time, so feeding the body with enough protein is wise. 

Many plant-based options are naturally free of animal fats, which can help with heart health in the long run. These foods are also linked to lower cholesterol levels. 

Ways to replace animal protein

Busy schedules might make it tricky for some people to figure out a plant-friendly menu that supplies adequate protein.

Tofu, beans, lentils, peas, nuts and tempeh are familiar to many who want to load up on muscle-building nutrients without relying on animal products.

“Unlike animal-based protein, these foods contain zero cholesterol and tend to be low in saturated fat, making them a smart choice for long-term health. Getting enough protein is as easy as enjoying meals you already know and love,” said Xavier Toledo, a registered dietitian with the Physicians Committee.

Wider acceptance

The survey revealed that more than half of respondents felt it was possible to gain muscle on a plant-based eating plan.

This marks a change from older attitudes that portrayed animal protein as the gold standard.

Despite strong acceptance among younger adults, the broader public still lags behind on the facts. That gap could close as research keeps highlighting the flexibility and benefits of plant-based diets.

The study is published in the American Journal of Clinical Nutrition.

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