As much as I would love to give you a definitive answer to the question, I can’t. For as much as I have read and researched the subject, I haven’t been able to find any concrete conclusions (as with many similar topics). This is because no research can really be done where the test subjects are identical. Even if you are testing the same person, their body will change day to day, hour to hour so the amount of protein the body will be able to absorb will be different. For example, you will be able to absorb more protein right after a workout than if you have been sedentary. Luckily, we have been able to get it down to some general numbers that have shown to be pretty accurate.

There are some rules of thumb to follow that have been created that I generally recommend to people. For males, it is usually said that we can absorb around 40 grams at a time. As I said earlier, if you just finished a workout your body will have a higher demand for protein, as compared to you being sedentary. Your body weight and level of workout intensity will also play a role in protein absorption. If you are a serious lifter, you should aim to get around 1.2 grams of protein per pound of body weight, per day. So if you weight 170lbs, you should be getting 204 grams of protein per day into your system. Post-workout you need to get anywhere between 25-40 grams of a complete protein source. If you pass your upper limit for the amount of protein that can be absorbed, you will just pee the leftover amino acids out.

Females are usually in the 20-25 grams of protein range for the amount that they can absorb at once. They typically weight less than males and have less muscle mass, so not as much as required for females. Something that females especially need to pay attention to when raising their protein intake is their calcium intake. Your kidneys must expend calcium in order to digest protein, so a high protein diet will have you burning through more calcium than usual.