SymbolismNZ wrote: »

To break this down from a medical science viewpoint..

Your body can only process so much protein in a given time period; there are tons of muscle building articles that state "It's rubbish, your body can consume as much protein as you push into it at any point in time" but the research indicates that your body can only really get the benefit of around 30-50 grams of protein in any particular eating session.

Study Referenced: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3197704/

TL;DR - they took two target groups of people, gave one group 30g of protein and another 90g of protein per sitting (3 to 5 hours between sitting) - there was no further increase in protein synthesis in those that ate 90g versus those that ate 30g. Those on 90g were probably gas champs though.

just a quick FYI ... although easily misunderstood, this isn't quite correct from a biochemistry standpoint. Your interpretation of the study is missing some information.

Just to add, for clarification purposes:

First, the study looked at muscle protein synthesis (repairing or removal of damaged proteins, and building new ones) - and did not look into what happens to protein in excess of what's required for MPS. It's untrue that all protein in excess of what's required for MPS will be converted to glucose - most will simply be absorbed for use later in the day or at night when we sleep and the real repair happens.

Also the study methodology required that for seventy-two hours prior to admission, participants were asked to maintain their normal diet and avoid strenuous activity. As such, there was little need for MPS (Muscle Protein Synthesis). Had these participants been involved in weight-training or daily exercise, the amount of protein that could be utilized for MPS would be higher.

Also of note - even for a non-exercising person, 30g of protein is a fair amount for one meal. Any studies I've seen trying to give an 'excess' of protein are offering 90-100g of protein at a time. That's a HUGE amount if you think about it. 100g of chicken breast, for example, has 31g of protein. You'd have to eat 12oz (3/4 of a lb!) of chicken breast in a single serving to hit the 90-100g threshold - which is phenomenally uncommon.

The maximum amount of protein we can ABSORB differs greatly from the maximum we can UTILIZE. Sure, a non-exercising person may only utilize 30g per meal, but they can absorb more. For someone that engages in weight-training or heavy exercise of any kind, there's a greater need for protein and they can actually utilize more than 30g.

As far as maximums, bodybuilders working for hypertrophy don't generally exceed 1g/lb of bodyweight, as studies show there's no benefit to protein consumed in excess of this / day. But for actual MPS and hypertrophy to occur, they MUST get protein at roughly that amount. If we could only use 30g/meal, a 240lb bodybuilder would require 8 meals of that amount to get that in - and we know they don't need to do that.

Bottom-line on protein per meal? The limit to how much protein per meal can be effectively used is likely similar to the amount that’s maximally effective for an entire days consumption. There's some excellent review on protein by Layne Norton, PhD - but he's moved them behind a subscriber paywall - so I can't link to his analysis and sources. But after a thorough review, I'm absolutely positive his review and the limit I mention above is correct.

SymbolismNZ wrote: »

Now the other thing with eating protein is that it can be turned into glucose if you have too much of it,

This is much more rare than people think. First, you'd need to eat a lot. Second, GNG (Gluconeogenesis) is a demand-driven process, not a supply-driven process. For excess protein to be converted to glucose and/or stored as fat, you'd need to have an excess of calories in addition to the excess of required protein - and most keto dieters don't do that, unless they're eating one very large meal per day.

Though it doesn't happen to everyone, where the increased blood glucose likely comes from in ingesting 'excess' protein is from a glucagon response, which occurs whenever we eat protein. Protein is insulinogenic, yes - but it's well known to also induce glucagon secretion. Because many of us are either insulin-resistant and/or insulin-deficient those people cannot mitigate the glucagon response and we end up with higher blood glucose as glucagon actually stimulates gluconeogenesis. So the issue isn't so much the 'excess' protein, but the meal itself. Again, this will ONLY be an issue for people with an impaired insulin-response.