There isn't a certain amount of protein that you can necessarily consume at once. It is true that your body can only utilize so much protein at one time (there isn’t an exact number value for everyone here), but that doesn't mean the rest is useless. Keep in mind though that there isn't much benefit in consuming too much protein for the day. Your body needs a certain amount and it's really important to get enough, but at the same time going overboard isn't helpful. However if you consume a decent amount of protein at once, it doesn't go to waste. Your body is pretty efficient at storing amino acids and slowing down digestion if you consume a larger amount of protein at one sitting.
We suggest to not be as concerned about your protein intake at once, but more so over the entire day. Your daily protein intake is going to be more important. Of course though we wouldn't suggest consuming an astronomical amount of protein at one time. A lot of people experience digestive issues from getting too much protein at once, or in a day. If you consume a lot of protein at once, it's just more likely that you are probably eating too much protein in total for the day.
- Matthew Mazzino, Registered Dietitian