How Much Protein Can Your Body Absorb? Here's How Much To Eat In One Sitting
If muscle growth is your goal, what you put on your plate is just as important as how much weight you're lifting at the gym. But besides filling up on lean proteins or sipping a protein shake after your workout, how you distribute your protein intake throughout the day can also affect how quickly you'll see results.
We reached out to a few experts to learn more about how much protein your body can actually absorb in a single sitting.
How much protein can your body absorb in one meal?
Before diving into the science, it's important to distinguish between protein absorption and protein utilization.
When you eat a big slab of steak, for example, it travels through your digestive tract. The protein that it contains is broken down into amino acids, which are absorbed into the bloodstream1 and used by the tissues throughout the body.
"The reality is you can absorb almost all of the protein that you consume," explains Mike T. Nelson, CSCS, CISSN, MSME, Ph.D., a human performance specialist.
The reality is you can absorb almost all of the protein that you consume.
On the other hand, Nelson points out that the amount of amino acids that can be used to fuel muscle growth2, or muscle protein synthesis (MPS), is limited.
He compares the process of muscle hypertrophy (aka muscle building) to an assembly line: A calorie surplus is needed to provide energy for the line, leucine (a type of branched-chain amino acid) is needed to turn it on via a gene called mTOR, and essential amino acids are used as the building materials for the new muscle tissue.
"Levels of leucine above 2.5 grams per meal will turn on [mTOR]," protein and amino acid requirements researcher Don Layman, Ph.D., explains on the mindbodygreen podcast. "If you don't meet that threshold, that protein consumption is a sense going to waste."
This means that the composition of your meal matters just as much as how many grams of protein you're getting in your daily diet.
There are a few other factors that can also impact how much protein your body is able to use for muscle growth1, including your age, body composition, and training status.
Interestingly, one 2015 study estimated that the amount of protein needed to maximize muscle growth3 was up to 0.4 gram per kilogram of body weight for young men, and up to 0.6 grams per kilogram for some older men. To put this into perspective, this means that a 150-pound man can require up to 27 to 41 grams (including 2.5 grams of leucine) to maximize hypertrophy, depending on their age.
Mary Sabat, M.S., RDN, L.D., points out that your overall protein needs can be influenced by a wide range of factors4, including your age, your physical activity level, the intensity and duration of your workouts, and your overall health status. Learn more about figuring out your personal protein needs here.
When to eat protein to build muscle
According to Nelson, you need amino acid levels to drop before you can restart the process of MPS. "If I want to turn a light switch on and off multiple times per day, I obviously need to turn it off before I can turn it back on again," he says, explaining that it's best to split your protein intake into several meals per day with a few hours between each to boost muscle growth.
There is some research to show that this becomes even more important the older you are since when mTOR is constantly activated, it may accelerate aging5.
There's no universal answer for how much protein you should eat per meal or even how many meals you should aim for each day.
According to one review, it's estimated that eating at least two to three meals with 25 to 30 grams of high-quality protein each could optimize MPS6 in healthy adults. On the other hand, the International Society of Sports Medicine advises eating at least 1.6 grams of protein per kilogram of body weight, spread over a minimum of four meals each day to maximize your body's anabolic response7, or muscle growth. This comes out to roughly 27 grams per meal for a 150-pound man.
Nelson emphasizes the importance of eating a variety of protein-rich foods during each meal to cover all your bases and round out your diet. Though protein-rich foods are your best bet for ramping up your intake, protein powder can also help fill in the gaps if you're in a pinch.
Besides how much protein you're eating each day, how you distribute your intake might also matter.
In fact, some research suggests that it may be best to squeeze more protein into your morning meal. According to a recent study published in the Journal of Nutrition, eating a high-protein breakfast8 and consuming less protein during dinner was more effective for muscle growth. Another animal study had similar findings, concluding that eating protein at breakfast might be better for maintaining muscle mass9.
Most digestible protein types
"Plant and animal proteins differ in their amino acid profile, and this affects their absorption rate and efficiency in building muscle," says Sabat.
She explains that animal proteins contain all of the essential amino acids needed to build and repair muscle tissues, whereas plant-based proteins may be lower in one or more of these amino acids10.
In addition to their amino acid profile, plant-based proteins also aren't digested or absorbed as efficiently. In fact, it's estimated that plant-based proteins have absorption rates11 ranging from 75 to 80% compared to around 90 to 95% for animal-based proteins like meat, fish, and poultry.
Though you definitely can still meet your protein needs for muscle growth on a vegan or vegetarian diet, it might require a bit more effort.
Sabat recommends consuming a variety of protein sources and combining them strategically, which can help ensure you're getting enough of the essential amino acids you need to reach your goals. Plant-based protein powders, such as pea protein powder, can also be a quick and convenient option to bump up your intake.
People who might not be able to absorb protein
Even if you follow dietary recommendations to a T, certain groups might have a hard time absorbing or using protein efficiently. This includes:
- Older adults: "As people age, their bodies become less efficient at digesting and absorbing protein, which can lead to decreased muscle mass12 and strength," says Sabat. She notes that this can increase the risk of falls and fractures, making it even more crucial to fit enough protein into your daily diet (pairing it with resistance training) when you get older.
- People with kidney disease: Because the kidneys are responsible for filtering waste products from the blood, kidney disease13 can impair the body's ability to use protein. Depending on your stage of kidney disease, a doctor might even recommend moderating or limiting your protein intake to prevent adverse effects on health.
- People with liver disease: The liver plays a major role in protein metabolism too. "In people with liver disease14, the liver may not be able to produce enough of the enzymes needed to break down and utilize protein," Sabat explains.
- People with digestive disorders: Several digestive issues can interfere with the digestion and absorption of certain nutrients, including protein. In particular, conditions like inflammatory bowel disease, celiac disease, Crohn's disease, and lactose intolerance can make it more challenging for the body to absorb protein efficiently15.
How much protein is too much?
While piling on the protein powder may seem like an easy way to boost muscle building, more is not always better when it comes to protein consumption.
"If you eat more protein than your body needs, the excess protein is not stored as protein," says Sabat, adding that excess protein is converted into glucose16 (aka sugar), which can be used as fuel or stored as fat. "Therefore, if you consistently eat more protein than your body needs and consume excess calories, the excess protein can contribute to fat gain." The same goes for other macronutrients.
For this reason, Sabat emphasizes the importance of enjoying protein as part of an overall balanced diet.
Can the body absorb more than 30 grams of protein?
According to Nelson, the claim that your body can only absorb 30 grams of protein per meal is a myth. Instead, he explains that you can absorb almost all of the protein that you consume, assuming your digestive system is working efficiently, but notes that the amount you can use for muscle growth in a single sitting is limited. Most studies show that about 25-40 grams of protein (with at least 2.5 grams of the amino acid leucine) is needed to maximize MPS, depending on factors like your age. So you can certainly eat more than 30 grams of protein per sitting—just make sure you're keeping your overall calorie intake in check.
How much protein can your body absorb in 24 hours?
Unless you have issues with nutrient absorption, your body should be able to absorb nearly all of the protein that you consume in 24 hours. However, only a limited amount can be used to build muscle mass, which can vary depending on factors like your age, body composition, and training status.
So how much protein can your body absorb? Unless you have a medical condition that interferes with digestion, you can probably absorb about as much protein as you consume. However, research suggests that the amount of protein used for muscle growth may be capped at around 25 to 40 grams per meal, including at least 2.5 grams of leucine, depending on factors like your age, health, and training status.
Therefore, it's best to eat several meals throughout the day rather than trying to squeeze all your protein into a single sitting. Enjoying a high-protein breakfast and pairing protein intake with resistance training can also help maximize muscle growth.
Rachael Ajmera, MS, RD is a registered dietitian and writer based in San Francisco. She holds a master's degree in Clinical Nutrition from New York University and an undergraduate degree in Dietetics.
Rachael works as a freelance writer and editor for several health and wellness publications. She is passionate about sharing evidence-based information on nutrition and health and breaking down complex topics into content that is engaging and easy to understand.
When she's not writing, Rachael enjoys experimenting with new recipes in the kitchen, reading, gardening, and spending time with her husband and dogs.