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 How Protein Absorption Rates Affect You
Many entities recommend eating extra protein to enhance muscle growth or prevent muscle loss. Some recommend over 2 grams of protein per kilogram (about 1 gram per pound) of body weight. However, eating more protein only helps if you can absorb it. This is often limited by how quickly the protein can be digested and absorbed in the gastrointestinal tract, which has some far-reaching implications:
How quickly can the body absorb amino acids from foods?
The gastrointestinal tract can absorb amino acids from the most digestible protein (whey protein) at around 10 grams per hour under ideal conditions. This rate will drop if you change the conditions or the protein source. For example, amino acids from egg protein get absorbed at around 4 grams per hour. For some other protein sources, it can be as low as 1.3 grams per hour.
The amount of protein you can get from food is limited.
If you multiply the absorption rates by 24 (hours per day), you get the amount you can absorb per day. So, you can absorb about 240 grams per day of whey protein. This can be a high limit depending on many factors, but it still is a limit.
This limit can drop to about 96 grams per day (4 grams/hour x 24 hours) for egg protein or even less for other protein sources. This is enough if all the amino acids are used for protein synthesis. But if amino acids need to also be energy sources, even 240 grams per day might not be enough. It is hard to build muscle without carbohydrates.
Some organs (including the brain) need carbohydrates to function. For most people, these organs use about 130 grams per day. If they don't eat enough carbohydrates, the body will break down amino acids to make carbohydrates for these functions.
If you do vigorous exercise (which requires glycolysis), it will demand even more carbohydrates. There is no guarantee that 240 grams of protein will leave enough amino acids for protein synthesis after satisfying these requirements. In some cases, the body will need to catabolize muscle for the amino acids to serve vital functions. This is why it can be difficult or even impossible to build muscle on low-carb diets. If you want to build muscle, you will get the best results if you include carbohydrates in your meal. Using protein efficiently often works better than just adding more protein.
As said before, if your body uses amino acids for energy, there might not be enough for protein synthesis. On the other hand, there are more than a few National Level and World Class powerlifters who are vegans. Also, many vegan weightlifters are much stronger than average. This is despite vegan protein sources being digested at slower rates.
It's because their vegan diets are inherently high in carbohydrates. It allows most if not all of the amino acids (depending on protein quality) to be used for protein synthesis. Even if the protein quality is mediocre, some amino acids will still be used for protein synthesis. This shows the protein-sparing effect of carbohydrates. Reducing carbohydrates simply means reducing Calories.
Absorbing 240 grams of amino acids yields no more than 960 non-fat Calories. This can potentially create a huge caloric deficit. A slower-digesting protein will produce less than half the amino acids per day. This cannot make enough carbohydrates to feed the brain and other organs that need it. So the body will have to break down some of its lean mass to balance out the shortage of amino acids. This is a starvation process.
So, low-carb diets cause weight loss because they create a shortage of Calories. In some cases, they cause muscle loss due to starvation. One meal may not be enough to provide your protein requirements.
When you chew food and swallow it, it can take up to 8 hours to pass through both the stomach and the small intestines. Also, about 95 to 98 percent of amino acids are absorbed in the small intestine.
So, the fastest digesting proteins will probably give less than 80 grams (10 grams per hour time 8 hours) in a meal. This is the most generous estimate under the most ideal conditions. A slower-digesting protein (such as egg protein) will deliver a little over 30 grams in a meal (4 grams per hour times 8 hours) under ideal conditions. If you eat one meal per day, this is probably not enough protein to sustain you. That is unless you eat enough carbohydrates to spare amino acids for protein synthesis. If you eat high protein and want more, add whey protein.
If you are eating more than 90 grams of protein per day, your absorption is probably more limited by the absorption rate than by the amount. So if you want more protein absorption, a faster-digesting protein (such as whey protein) would be better. It will also help if you take the whey protein on an empty stomach.
Protein is crucial for maintaining muscle mass and other vital functions. However, eating more protein does not guarantee that you will absorb more protein. You can help this situation by eating carbohydrates. This will spare the amino acids for muscle growth instead of quandering them on energy production. Other articles |
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