The Limits of Protein Absorption in a Single Meal

How much protein can you absorb in one meal? I had a conversation about this topic on protein absorption with my doctor, and he said that the body can only absorb 15 grams of protein per sitting.

I was wondering if it is true?

It is unfortunate that some doctors continue to mislead people on subjects like these, that are obviously not their specialty.

Just because someone is a doctor doesn’t mean that they are the know-all source of information for everything that has to do with the human body.

If that were the case, we wouldn’t have all the different kinds of doctors and nutritionists we have.

One guy, called a doctor, would know everything and you would have all these other jobs.

The truth is no one knows how much a person can absorb because it varies from one person to the next.

Let's talk common sense here for a minute: Do you think that professional athletes from all over the world could accumulate the amount of muscle they do on what would total out to be about 45g a day by doctors standards?

They actually probably consume more like six times (at least) that amount in order to grow the muscle they do.

“Yeah, but they’re all on steroids?”

First off, that’s not true.

Yes, like it or not, steroids are a part of any competitive sport at some level and to say otherwise would be a very ignorant statement.

However, I don’t think it would be a stretch to say that in this era the majority of athletes are clean in most sports (now 10-15 years ago may be a different story).

Yes, steroids can help you gain massive amounts of muscle, but they themselves do not directly cause muscle gain.

They basically make your body much more efficient at processing and using the raw materials you give it, such as protein.

You can take all the steroids in the world you want to and if you don’t have enough building blocks for muscle (protein) you aren’t going to grow.

Sufficient and consistent protein intake (with or without steroids) is directly proportional to muscle mass.

Think of it in terms of building a house.

To build a house you need two things: workers & materials.

Let's say you are building a house and you want to get it built as quickly as possible.

So you hire 100 guys to come build the house, they all show up on Monday morning and the materials aren’t on site.

What happens? Nothing right?

They don’t have anything to build with. Now, relate that back to your body.

You want to build a lot of muscle real fast and so you go bust your ass in the gym everyday, but you don’t give your body the protein & calories it needs to build muscle.

What happens? Nothing.

To build muscle you have to have two things: workers & materials (resistance training & protein).

Now, let's examine the house analogy once again. Let’s say this time you have your 100 workers show up on Monday morning and you do have the materials there, except you only have enough for half a day's work.

What happens at noon?

The guys have used up all the materials and can’t build any more of your house, their progress was limited from the get-go.

It ends up being wasted labor. See where I’m going with this?

You have to have enough protein to build throughout the day or you are going to be limiting your potential and wasting your hard work.

This is what happens when you abide by the “You can only absorb 15 grams of protein per sitting” mentality.

Your body needs those proteins and amino acids.

Without the proper nutrient intake, you are severely limiting your progress before you even get started.

The fact is, there are no studies that have ever been done that conclusively prove how much whey protein powder a person can assimilate in one sitting.

The reason concrete data is unavailable on this subject is because people are all different when it comes to protein digestion.

The amount of protein your body can absorb is dependent on many factors.

Age, body weight, sex, muscle mass, activity level and type of protein are all factors that decide how much protein your body will actually absorb in one sitting.

The research that has been done (1) does not take all of these individual factors into play.

There are just way too many individual factors and differences between people to conclusively prove how much protein any one person can assimilate.

The bottom line is everyone is different.

There is way too much variance in the individual factors of people to make a general statement like “You can only absorb 15 grams at one sitting”.

Anyone who does is making unintelligent generalizations about protein digestion and not looking at the big picture.

Protein Absorption: How Does It Work?

Protein absorption is a process that breaks down dietary proteins into smaller components that can be absorbed by and distributed to the body. Here's a quick overview:

Digestion in the Stomach:

The process begins in the stomach, where gastric acid and enzymes, such as pepsin, break down dietary proteins into smaller forms, including peptides and amino acids.

Absorption in the Small Intestine:

Then, we move to the small intestine, which is where the majority of protein absorption occurs. 

The small intestine is lined with finger-like projections called villi, and these villi are covered with even smaller projections called microvilli. 

These structures increase the surface area available for nutrient absorption.

Amino acids, which are the building blocks of proteins, and small peptides are absorbed through the villi and microvilli into the bloodstream.

Distribution and Utilization:

Once absorbed, amino acids travel to the liver via the bloodstream. 

The liver plays a central role in regulating amino acid levels in the blood and can release amino acids back into the bloodstream as needed.

Amino acids are then circulated throughout the body, reaching various tissues and cells. Cells use these amino acids for a variety of functions, including protein synthesis, energy production, and other metabolic processes.

So ... How Much Protein Can You Absorb in One Meal?

Typically, even a beginner male athlete can absorb 25 grams of protein per meal, however this is a “jumping off” point, a minimum.

Keep in mind that it is most likely possible for some people to absorb much more than 25 grams, depending on their individual factors we discussed earlier.

When I am trying to gain muscle I personally use Level-1 (2.5 scoops) in water as a staple for at least three meals throughout the day to make absolutely sure I am getting enough quality protein.

I may go a little overboard, but I make sure I’m not on the short end of the scale when it comes to stimulating muscle protein synthesis.

Many pro bodybuilders I know consume more than that at each meal!

The point here is that protein breakdown and absorption are different for each individual person.

There is absolutely no way to determine a set protein absorption amount for everyone to absorb and in my opinion it was extremely irresponsible for your doctor (or anyone else) to attempt to do so.

It seems a lot of people, especially medical doctors, have a problem these days with saying the phrase “I don’t know.” It’s very unfortunate.

How To Maximize Protein Absorption

The protein absorption process happens “behind the scenes” but there are things that you can do to boost that absorption to move the process along.

Select Whole Proteins

Opt for whole protein sources containing all essential amino acids, such as meat, fish, eggs, and dairy.

These sources provide a complete array of amino acids necessary for various bodily functions.

Distribute Protein Intake

Eat protein consistently throughout the day rather than concentrating it in a single meal. 

This ensures a steady supply of amino acids and helps your body use protein more efficiently.

Adopt Healthy Eating Habits

Practice regular and mindful eating, such as thoroughly chewing food so that it’s easier to break down the road. 

Establishing consistent eating patterns, reducing stress, and avoiding intense exercise immediately after meals can also help your overall digestion and nutrient absorption.

Consider Protein Powders

Fast-absorbing proteins, such as whey protein hydrolysates found in protein powders, can be beneficial for quick amino acid delivery. 

Not only are you getting more protein in a healthy way, but high-quality powders have other nutrients to help with digestion, too.

These powders can be particularly useful during workouts when a rapid protein source is the goal.

Digestive Enzyme Supplements

Supplementing with digestive enzymes, and potentially incorporating probiotics, may also help with the breakdown of proteins and improve amino acid levels in the bloodstream. 

If you tend to have digestive issues to begin with, this one may be especially valuable to you.

How Much Is Too Much?

While your goals may demand that you get more protein in your diet, your body does have limits. 

Like most foods, it’s important to still take a balanced approach to your protein intake. 

For example, eating more protein than your body needs may lead to excess glucose production and fat storage, which is a bit counterproductive.

While protein is not a direct source of glucose, the body can convert excess protein into glucose through a process called gluconeogenesis. 

This can contribute to an increase in blood sugar levels, which may not be ideal for individuals trying to manage conditions like diabetes or lose weight.

There is also concern that consuming too much protein over the long term may put a strain on the kidneys, especially in individuals with pre-existing kidney conditions. 

You can include protein as part of a balanced diet to avoid excess calories, stay full, and provide your body with what it needs without overdoing it.

If you have specific health concerns or dietary goals, it's always a good idea to consult with a healthcare professional or a registered dietitian who can provide personalized advice based on your individual needs.

Wrapping It Up

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1. Phillips, S.M., Physiologic and molecular bases of muscle hypertrophy and atrophy: impact of resistance exercise on human skeletal muscle (protein and exercise dose effects). Appl Physiol Nutr Metab, 2009. 34(3): p. 403-10.