THE “PROTEIN ABSORPTION” MYTH
A quick Google search on protein absorption numbers will yield all kinds of opinions and numbers. A recommendation commonly thrown around by “experts” is to limit your intake to no more than 30 to 40 grams of protein per meal, as any more will be discarded by the body.
This type of “one-size-fits-all” advice smacks of nonsense.
I highly doubt an NFL linebacker’s body deals with protein intake in exactly the same way as a 120-pound weakling’s. Protein needs due to lifestyle and lean mass should influence the matter of protein metabolism, right?
Additionally, if it were true that a person can only absorb a relatively small amount of protein in one meal, then “super-dosing” daily protein needs into two to three meals would result in protein deficiencies. This assumption begs the question of how the human species survived the hunter-gatherer days when we experienced regular feasts and famines, but the body is incredibly adaptive.
To better evaluate the issue at hand, let’s look at what happens when you eat protein.
First, your stomach uses its acid and enzymes to break the protein down into its building blocks, amino acids. These amino acids are transported into the bloodstream by special cells that line the intestines and are then delivered to various parts of the body. Your body only has so many transporter cells, which limits the amount of amino acids that can be infused into your blood every hour.
This is what we’re talking about with “protein absorption,” by the way: how quickly our bodies can absorb the amino acids into our bloodstreams.
As you know, the human body absorbs different proteins at different rates. According to one review, whey clocks in at 8 to 10 grams absorbed per hour, casein at 6.1, soy at 3.9, and egg at 1.3.34 These numbers aren’t completely accurate due to the complexities involved in measuring protein absorption, but they lend insight nonetheless: certain proteins are absorbed slowly, whereas others can be absorbed quickly.
Another fact relevant to the current discussion is that food substances don’t move uniformly through the digestive tract, and they don’t leave sections in the same order that they arrived in.
For instance, the presence of protein in the stomach stimulates the production of a hormone that delays “gastric emptying” (the emptying of the food from the stomach) and that slows down intestinal contractions.
This causes food to move more slowly through the small intestines, where nutrients are absorbed, and this is how your body buys the time it needs to absorb the protein you eat. Carbohydrates and fats can move through and be fully absorbed while your body is still working on the protein.
Once the amino acids make it into the bloodstream, your body does various things with them, such as grow and repair tissues, and it can also temporarily store (up to about 24 hours or so) excess amino acids in muscle for future needs.
If amino acids are still in the blood after doing all of the above, your body can break them down into fuel for your brain and other cells.
Now, how does all that relate to strict claims about how much protein can be absorbed in one meal? Well, such claims are usually based on one of two things:
An ignorance of how food moves through the digestive system.
Some people believe that all foods move through the small intestines in 2 to 3 hours and thus also believe that even if you ate even the type of protein that can be absorbed the quickest—at a rate of 8 to 10 grams per hour—you could only absorb 25 to 30 grams of it before it passes to the large intestine to be disposed of. According to this line of thinking, slower-digesting proteins result in even fewer grams absorbed into the bloodstream.
Well, as we now know, your body is smarter than that, and it regulates the speed at which protein moves through the small intestines to ensure it can absorb all of the available amino acids.
References to studies relating to the anabolic response to protein consumption.
A study commonly cited in connection with protein absorption showed that 20 grams of post-workout protein stimulated maximum muscle protein synthesis in young men.
That is, eating more than 20 grams of protein after working out did nothing additional in terms of stimulating more muscle growth.
The most obvious flaw in this argument is you can’t use studies on the anabolic response to protein consumption to extrapolate ideas about how much we can absorb in one sitting. Acute anabolic responses to eating protein just don’t give us the whole picture.
Absorption relates to the availability of amino acids over extended periods of time, which prevents muscle breakdown and provides raw materials for growth. And, as we now know, our body doesn’t just throw away all of the amino acids it can’t immediately use: it can store them for later needs.
Further supporting this position is a study conducted by researchers at the Human Nutrition Research Center.
It had 16 young women eat 79 percent of their daily protein (about 54 grams) in one meal or four meals over the course of 14 days. Researchers found no difference between the groups in terms of protein synthesis or degradation.
Furthermore, if we look at the amount of protein used in the above study relative to body weight, it comes out to about 1.17 grams per kilogram. Apply that to a man weighing 80 kilograms (176 pounds), and you get about 94 grams of protein in one sitting. While this isn’t definitive scientific proof, it’s food for thought.
Research on the style of dieting known as intermittent fasting is also relevant. This style of dieting has people fasting for extended periods, followed by anywhere from 2- to 8-hour “feeding windows.” One study on this method of meal timing found that eating the entire days’ worth of protein in a four-hour window (followed by 20 hours of fasting) didn’t have a negative impact on muscle preservation.
So, as you can see, it’s hard to put an accurate cap on how much protein your body can absorb in one meal. It’s definitely a hell of a lot more than the 20 to 30 grams that some people claim.
All that said, however, it turns out that eating smaller amounts of protein more frequently may be superior to larger amounts in fewer meals…
A quick Google search on protein absorption numbers will yield all kinds of opinions and numbers. A recommendation commonly thrown around by “experts” is to limit your intake to no more than 30 to 40 grams of protein per meal, as any more will be discarded by the body.
This type of “one-size-fits-all” advice smacks of nonsense.
I highly doubt an NFL linebacker’s body deals with protein intake in exactly the same way as a 120-pound weakling’s. Protein needs due to lifestyle and lean mass should influence the matter of protein metabolism, right?
Additionally, if it were true that a person can only absorb a relatively small amount of protein in one meal, then “super-dosing” daily protein needs into two to three meals would result in protein deficiencies. This assumption begs the question of how the human species survived the hunter-gatherer days when we experienced regular feasts and famines, but the body is incredibly adaptive.
To better evaluate the issue at hand, let’s look at what happens when you eat protein.
First, your stomach uses its acid and enzymes to break the protein down into its building blocks, amino acids. These amino acids are transported into the bloodstream by special cells that line the intestines and are then delivered to various parts of the body. Your body only has so many transporter cells, which limits the amount of amino acids that can be infused into your blood every hour.
This is what we’re talking about with “protein absorption,” by the way: how quickly our bodies can absorb the amino acids into our bloodstreams.
As you know, the human body absorbs different proteins at different rates. According to one review, whey clocks in at 8 to 10 grams absorbed per hour, casein at 6.1, soy at 3.9, and egg at 1.3.34 These numbers aren’t completely accurate due to the complexities involved in measuring protein absorption, but they lend insight nonetheless: certain proteins are absorbed slowly, whereas others can be absorbed quickly.
Another fact relevant to the current discussion is that food substances don’t move uniformly through the digestive tract, and they don’t leave sections in the same order that they arrived in.
For instance, the presence of protein in the stomach stimulates the production of a hormone that delays “gastric emptying” (the emptying of the food from the stomach) and that slows down intestinal contractions.
This causes food to move more slowly through the small intestines, where nutrients are absorbed, and this is how your body buys the time it needs to absorb the protein you eat. Carbohydrates and fats can move through and be fully absorbed while your body is still working on the protein.
Once the amino acids make it into the bloodstream, your body does various things with them, such as grow and repair tissues, and it can also temporarily store (up to about 24 hours or so) excess amino acids in muscle for future needs.
If amino acids are still in the blood after doing all of the above, your body can break them down into fuel for your brain and other cells.
Now, how does all that relate to strict claims about how much protein can be absorbed in one meal? Well, such claims are usually based on one of two things:
An ignorance of how food moves through the digestive system.
Some people believe that all foods move through the small intestines in 2 to 3 hours and thus also believe that even if you ate even the type of protein that can be absorbed the quickest—at a rate of 8 to 10 grams per hour—you could only absorb 25 to 30 grams of it before it passes to the large intestine to be disposed of. According to this line of thinking, slower-digesting proteins result in even fewer grams absorbed into the bloodstream.
Well, as we now know, your body is smarter than that, and it regulates the speed at which protein moves through the small intestines to ensure it can absorb all of the available amino acids.
References to studies relating to the anabolic response to protein consumption.
A study commonly cited in connection with protein absorption showed that 20 grams of post-workout protein stimulated maximum muscle protein synthesis in young men.
That is, eating more than 20 grams of protein after working out did nothing additional in terms of stimulating more muscle growth.
The most obvious flaw in this argument is you can’t use studies on the anabolic response to protein consumption to extrapolate ideas about how much we can absorb in one sitting. Acute anabolic responses to eating protein just don’t give us the whole picture.
Absorption relates to the availability of amino acids over extended periods of time, which prevents muscle breakdown and provides raw materials for growth. And, as we now know, our body doesn’t just throw away all of the amino acids it can’t immediately use: it can store them for later needs.
Further supporting this position is a study conducted by researchers at the Human Nutrition Research Center.
It had 16 young women eat 79 percent of their daily protein (about 54 grams) in one meal or four meals over the course of 14 days. Researchers found no difference between the groups in terms of protein synthesis or degradation.
Furthermore, if we look at the amount of protein used in the above study relative to body weight, it comes out to about 1.17 grams per kilogram. Apply that to a man weighing 80 kilograms (176 pounds), and you get about 94 grams of protein in one sitting. While this isn’t definitive scientific proof, it’s food for thought.
Research on the style of dieting known as intermittent fasting is also relevant. This style of dieting has people fasting for extended periods, followed by anywhere from 2- to 8-hour “feeding windows.” One study on this method of meal timing found that eating the entire days’ worth of protein in a four-hour window (followed by 20 hours of fasting) didn’t have a negative impact on muscle preservation.
So, as you can see, it’s hard to put an accurate cap on how much protein your body can absorb in one meal. It’s definitely a hell of a lot more than the 20 to 30 grams that some people claim.
All that said, however, it turns out that eating smaller amounts of protein more frequently may be superior to larger amounts in fewer meals…
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