This is a question that came to mind for me after I had a gastric bypass last year and was advised to start using protein supplements. Most protein supplements seem to offer about 20 – 30 grams of protein per serving, but some offer considerably more than that. But are the supplements that offer more better? How much protein can we really absorb at one time?
I was told by my bariatric surgeon that we can only absorb about 40 grams of protein at a time. Other people have told me they were given similar advice by their surgeons or dieticians. Some were told they could only absorb about 30 grams of protein at a time. One person was told that people can only absorb 20 grams at a time. Another person was told that there was no limit. Since doctors and dieticians don’t agree, what is the answer?
Well, I went in search of the answer. I must admit, it was hard to find information. I looked online and I found lots of people expressing their opinions on the matter, but found little scientific data. Can it really be that no one has actually studied this?
Here is what I did find, however. The American Society for Metabolic and Bariatric Surgery states that while it is common belief that people can only absorb about 30 grams of protein at a time, there is no scientific evidence to back this up. There is no reason to think a person could not absorb 50 grams or 60 grams or even more at a time.
The ASMBS suggests that the belief that people can only absorb 30 grams at a time may be simply based on the fact that that’s the amount a person might reasonably consume at one meal. It’s not that you can’t absorb more, it’s just that you probably can’t eat more. Unless, of course, you are using a high protein supplement.
How much protein we can absorb at a time might not really be the right question to ask. A better question might be, how much protein should we consume at one time. To answer that question, it is necessary to understand how our bodies use protein.
When we eat protein, we break it down for the amino acids it contains. We use those amino acids to build and maintain our body tissues. After eating some protein, we generally utilize all the amino acids we’ve consumed in just a few hours. Then we need more. If we don’t get more, we start to break down our own body tissues to get amino acids. Mostly we break down muscle.
For this reason, we need to take in protein regularly throughout the course of the day. The average person needs about 50 – 55 grams of protein per day, but it wouldn’t do to eat 50 grams of protein for breakfast and then eat no more for the rest of the day. We would use up those amino acids by lunchtime and then we would start to break down our own muscles to get more. It would make more sense to eat 10 grams for breakfast, 20 for lunch, another 20 for dinner, and 5 for a bedtime snack.
Of course, we could go ahead and have 50 grams for breakfast and then eat some more at lunch and some more at dinner. But a breakfast that contains 50 grams of protein is probably going to have a lot of calories. Unless you are trying to gain weight, there is no real sense in eating more protein than you need. You’ll just be getting unnecessary calories.
American Society for Metabolic and Bariatric Surgery. http://www.asbs.org/Newsite07/resources/bgs_final.pdf. ASMBS Guidelines.