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.

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.

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.

"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.

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.

"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.

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.

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.