How Much Protein Can The Human Body Absorb In One Sitting?

No there aren't any studies that found a limit to the amount of protein you can digest, if that's what you're asking.

Here is the best info I could find, this is by John Berardi

While it's obvious that the protein need question is an academic one, I want to address it here because the answer may shock you.

Before we talk about specific numbers, I need to give you a little background on how to measure protein needs. Measuring protein needs in different populations is usually accomplished by the nitrogen balance technique. This technique involves measuring the amount of nitrogen ingested (in protein sources), as well as measuring or estimating the amount of nitrogen excreted in the urine, sweat, and feces.

If the amount of nitrogen going into the body is greater than the amount of nitrogen leaving the body, it's said that the person is in positive nitrogen status. It's then assumed that the surplus protein retained in the body has been used to build up body tissues.

If the amount of nitrogen coming in is equivalent to the nitrogen going out, it's said that the person is in nitrogen balance. It's then assumed that the person is eating just enough protein to prevent deficiency but not enough to build additional tissue.

If the amount of nitrogen going into the body is less than the amount of nitrogen leaving the body, it's said that the person is in negative nitrogen status. It's then assumed that the person is protein deficient and in time they will begin to break down muscle tissue and, eventually, organ mass to provide for their basic amino-acid needs.

It's therefore important to recognize that most protein-need studies look for the protein intakes at which people are in nitrogen balance, or just enough to prevent them from being deficient.

From these nitrogen-balance experiments, it's been recommended that untrained individuals consume 0.8g of protein per kg of body mass to meet their need.

Again, this is the amount of protein needed to keep them in balance while staving off the dreaded negative protein status (which can lead to protein malnutrition, muscle and organ wasting, and eventual death).

With respect to athletic needs, the work of Lemon, Tarnopolsky and colleagues has given some indication that athletes do require more protein (Lemon et al 1981, Tarnopolsky et al 1988, Tarmonpolsky et al 1992, Lemon et al 1997). This classic research indicates that during intensive training, strength and endurance athletes may need somewhere between 1.4 - 2.0 g of protein per kg of body mass to maintain nitrogen balance.

But what about all the athletes and weightlifters out there that consume fewer protein grams than the recommended 1.4 - 2.0 g of protein per kg of body mass? If they really needed those 1.4 - 2.0g/kg, wouldn't they be wasting away and dying? Since they're not, they must not need all that protein. What's the deal?

As Rennie and colleagues have pointed out, there are several problems when trying to apply the Lemon and Tarnoposky data to habitual exercisers. First, the studies by Lemon and Tarnopolsky were done on athletes undergoing new training programs.

While they were recreationally active before the study began, the training stimulus (strength training in some studies, endurance training in others) was novel, most likely causing a short-term increase in protein need, an increase that would not persist in the long-term (Rennie et al 1999, 2000). In other words, Rennie argues that while a new exercise program (whether strength or endurance exercise) may increase protein need acutely, chronic exercise probably doesn't increase protein need at all.

Now before you start hatin' on Rennie, it's important to understand that this guy is a protein research legend. Type his name into Medline and you'll get a couple hundred protein-related research publications. Beyond his excellent reputation, his ideas do have both theoretical and research support.

Specifically, the research of Butterfield and Calloway suggests that athletes may actually need less protein due to an increase in protein efficiency that may accompany chronic training (Butterfield and Calloway 1984). What this means is that athletes may actually get more efficient in their protein use (i.e. increased anabolic efficiency) and therefore may need less protein than the 0.8g/kg required for sedentary individuals!

Is this Rennie guy crazy? Probably not! Then why do his comments fly in the face of what athletes and weightlifters know; namely that a higher-protein diet helps pack on muscle mass and helps promote a favorable body composition? Well, actually, they don't! If you think so, you haven't taken a lesson from our earlier discussion. Namely, you're still confusing need with optimization.

An athlete may need less protein to stay alive but he/she should consume more protein to optimize performance and body composition. Therefore, when I'm asked how much protein an athlete needs, my best response is that it doesn't matter! Asking "How much protein does an athlete need?" is much like asking the question "How much does a student need to study for an exam?"

Since a student only needs to pass their exam to remain a student, the proper answer would be "however much it takes to score a 60%." However, very few students want to earn only a 60%. Therefore the best question would be "How much does a student need to study to get an A on their exam?"

Optimization Of Protein Intake

In the above section, I've indicated that athletes may actually need fewer protein grams per day than the typical sedentary dose of 0.8g/kg. Actually, the Butterfield study suggests an exact number: 0.65g/kg.

In calculating the exact amount of protein they might recommend to maintain nitrogen balance, a 200lb athlete who trains consistently would find that they only need a measly 59g of protein to prevent nitrogen losses and protein malnutrition.

So, for those of you who staunchly believe that you're only required to eat enough protein to meet your needs, go right ahead and reduce your protein intake from 2.0g/kg to 0.65g/kg. In the meantime, I'll be encouraging everyone else to actually increase his or her protein intake beyond the current 2.0g/kg recommendation.

If this recommendation seems excessive, it's because you have a narrow view of how protein fits into one's dietary strategy. You're looking at protein in the same narrow way that people used to look at vitamin C; essential at a specific dose but conferring no additional benefits with a higher intake.

With vitamin C, we all know it's important to consume enough of it (at least 10mg/day) to prevent scurvy. However, it's also commonly known there are a host of health benefits associated with much higher doses (200mg/day or more) including a reduced risk of cancer, increased HDL cholesterol, reduced risk of coronary artery disease, and a reduced duration of cold episodes and severity of symptoms.

Like vitamin C, instead of thinking of protein as a macronutrient that provides no benefit beyond preventing protein deficiency, we need to recognize the benefits of eating protein (at any dose).

Increased Thermic Effect of Feeding �" While all macronutrients require metabolic processing for digestion, absorption, and storage or oxidation, the thermic effect of protein is roughly double that of carbohydrates and fat. Therefore, eating protein is actually thermogenic and can lead to a higher metabolic rate. This means greater fat loss when dieting and less fat gain during overfeeding.

Increased Glucagon �" Protein consumption increases plasma concentrations of the hormone glucagon. Glucagon is responsible for antagonizing the effects of insulin in adipose tissue, leading to greater fat mobilization. In addition, glucagon also decreases the amounts and activities of the enzymes responsible for making and storing fat in adipose and liver cells. Again, this leads to greater fat loss during dieting and less fat gain during overfeeding.

Increased IGF-1 �" Protein and amino-acid supplementation has been shown to increase the IGF-1 response to both exercise and feeding. Since IGF-1 is an anabolic hormone that's related to muscle growth, another advantage associated with consuming more protein is more muscle growth when overfeeding and/or muscle sparing when dieting.

Reduction in Cardiovascular Risk �" Several studies have shown that increasing the percentage of protein in the diet (from 11% to 23%) while decreasing the percentage of carbohydrate (from 63% to 48%) lowers LDL cholesterol and triglyceride concentrations with concomitant increases in HDL cholesterol concentrations.

Improved Weight-Loss Profile �" Brand spankin' new research by Layman and colleagues has demonstrated that reducing the carbohydrate ratio from 3.5 - 1 to 1.4 - 1 increases body fat loss, spares muscle mass, reduces triglyceride concentrations, improves satiety, and improves blood glucose management (Layman et al 2003.

If you're at all interested in protein intake, you've gotta go read the January and February issues of the Journal of Nutrition. Layman has three interesting articles in the two journals).

Increased Protein Turnover �" As I've discussed before in my article Precision Nutrition, all tissues of the body, including muscle, go through a regular program of turnover. Since the balance between protein breakdown and protein synthesis governs muscle protein turnover, you need to increase your protein turnover rates in order to best improve your muscle quality.

A high protein diet does just this. By increasing both protein synthesis and protein breakdown, a high protein diet helps you get rid of the old muscle more quickly and build up new, more functional muscle to take its place.

Increased Nitrogen Status �" Earlier I indicated that a positive nitrogen status means that more protein is entering the body than is leaving the body. High protein diets cause a strong positive protein status and when this increased protein availability is coupled with an exercise program that increases the body's anabolic efficiency, the growth process may be accelerated.

Increased Provision of Auxiliary Nutrients �" Although the benefits mentioned above have related specifically to protein and amino acids, it's important to recognize that we don't just eat protein and amino acids �" we eat food.

Therefore, high protein diets often provide auxiliary nutrients that could enhance performance and/or muscle growth. These nutrients include creatine, branched chain amino acids, conjugated linoleic acids, and/or additional nutrients that are important but remain to be discovered. This illustrates the need to get most of your protein from food, rather than supplements alone.

Conclusion

Looking over this list of benefits, isn't it clear that getting lots of protein would be advantageous to anyone's training goals? Since a high protein diet can lead to a better health profile, an increased metabolism, improved body composition, and an improved training response, why would anyone ever try to limit their protein intake to the bare minimum necessary to stave off malnutrition?

It seems to me that whether someone's on a hypoenergetic diet or a hyperenergetic diet, the one macronutrient they would want to be sure to overeat would be protein. Instead, their protein prejudice often leads most trainees to look for what they consider the bare minimum of protein, and then overeat carbohydrates and fats instead. That's a big performance and body composition mistake.

I have yet to meet a healthy man or woman that couldn't use more protein in his or her diet. It's high time we drop our prejudiced attitude toward protein and start giving it the respect it deserves.

Now get outta my lab �" I've got work to do and you've gotta go eat some protein.

John Berardi

there is no maximum. if anyone tells you otherwise, they're pissing on your training shoes. the number 40grams used to be thrown around a lot. this was based on NOTHING. at best, any top number for protein derived by the medical community has to do with kidney function. these studies were done on ppl with kidney disease, and found that ingesting a high protein diet was damaging to the kidneys. however, a healthy kidney has no problem dealing with very large quantities of protein, and actually becomes more efficent at dealing with protein the more you eat (just like a muscle, it adapts to a stimulus). eat your fill, no more, no less. this will be a bit different for everyone, based on training needs, disease state, metabolism, genetics, etc.). on a personal note, i know for myself (again, this is a very individualized thing) i won't get lean unless i ingest at least one gram of protein per pound of body weight (total bw, not lean mass). the higher i go above this number, the leaner i get. until about 220 grams per day, then i start to feel like shit. now, that probably has little to do with the amount of protein per se, but rather the totality of digestive stress on my system.

To me the main inportance is keeping Protein Synthesis going on throughout the day as often as possibe......I weigh about 225 Lb's at 5'-10 1/2' ....bf % Is About 9% +/- ......Take in anywhere from a low of 25gm's to a high of 35gm's of quality protein every 2-3 hr's throughout the day.....This usally amounts to about 7-8 dosages of protein per day......giving me a daily total of between 175-225 +/- gms of protein per day.....

It's my understanding that if you take in to much protein in one setting you'll either excrete the unused portion as waste product, or store the unused portion as adipose tissue......Please correct me if I'm wrong....:-)

It is because of my above believe that I put some much importance on the value of keeping protein synthesis active as long durring your day as possible.....while all the while only giving your body an amount ot protein that it can handle in one paticular meal......JMO....:-)

Peace Out!

Posted by: pa-muscle

To me the main inportance is keeping Protein Synthesis going on throughout the day as often as possibe......I weigh about 225 Lb's at 5'-10 1/2' ....bf % Is About 9% +/- ......Take in anywhere from a low of 25gm's to a high of 35gm's of quality protein every 2-3 hr's throughout the day.....This usally amounts to about 7-8 dosages of protein per day......giving me a daily total of between 175-225 +/- gms of protein per day.....

It's my understanding that if you take in to much protein in one setting you'll either excrete the unused portion as waste product, or store the unused portion as adipose tissue......Please correct me if I'm wrong....:-)

It is because of my above believe that I put some much importance on the value of keeping protein synthesis active as long durring your day as possible.....while all the while only giving your body an amount ot protein that it can handle in one paticular meal......JMO....:-)

Peace Out!

Newer studies in pulse feeding of protein indicate especially in older athletes, that greater gains in muscle may be achieved by consuming the majority of protein in only 1 or two of the days meals. I have come to believe that it's not so much the protein per meal but rather the total grams of protein ingested in a given 24 hour peroid. I just used 24 hours as an example time frame without any reference in science.

Hey bro ....:-) if you come across any studies that back up your opinion....please post and let us know......:-)

Peace Out!

Here is a thread that touches a bit on pulse feeding of protein.

https://www.growxxl.com/nutrition/how-much-protein-can-the-human-body-absorb-in-one-sitting