I have a local FB keto group and one member keeps insisting that protein is his most important macro and that he eats that more than fat. That is fine for him, but he keeps saying that if people don’t get enough protein then the body will take it from the muscles.
There are a lot of myths about protein.
There is an obvious one that you need to eat muscles (protein) to build muscles. It’s a bit like the eat fat to get fat, or eat your greens to turn green.
ApexOnKeto:
Can someone please clarify this protein issue for me so that I can report accurate information back to my group? I don’t want to argue with this guy, but I feel like he’s giving incomplete/inaccurate information.
I’ll do my best.
We use dietary protein for 4 purposes, we break it into amino acids and use them to maintain our existing protein structures, we also use them to make additional protein structures (like hypertrophic muscle building), we strip off the nitrogens in amino acids and use the remaining carbohydrate to make glucose if we need to make some, and finally we waste the excess for fuel.
The reality is that proteins are massive complex molecules that become easily miss-folded and damaged over time, so we evolved to replace old protein structures with new ones on an ongoing basis. This continual protein cycling sets the largest minimum requirement for new sources of amino acid building blocks, and that sets the minimum amount you must have every day.
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The daily minimum amount of protein that you need was determined by Rand et al 2003 Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults to be between 0.30g/kg (LBM) and
1.0g/kg (LBM)
Let’s try a thought experiment - what is the maximum protein that an imaginary man with 80 kgs LBM would need.
At 80 kgs of lean mass (that’s my LBM), 80g is the MOST you need to account for protein turnover. That is those two outliers on the far right of the 0 balance line in the Rand data (remember there is also a mutant down the other end who gets enough at 0.30g/kg LBM too).
If you are building new muscle you will need a little more. If you are working out as a full time job, and building an impressive rig to do the next wolverine movie you will put on let’s say 12 kgs of muscle over a 6 month period … that will take 2 kgs of raw amino acids, in 150 days - that would be a total of 13g extra every day.
So let’s say our imaginary guy is going from 80kg to 92kgs you would need roughly 80g + 13g = 93g per day.
If you don’t eat around 150g of carbs a day (and really who among us is?) then you will also need some dietary protein to be turned into glucose to keep your brain alive.
Let’s say you are eating zero carbs, to take this argument to it’s absolute extreme. There is science showing exactly how much protein you will need. This was done by Geroge Cahill in his 1970 Starvation in Man study.
He studied the fuel flows using direct catheterization in a subject eating nothing, so subsisting only on body fat, and in the first 24 hours he used 75g a day of muscle protein to turn into glucose.
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By the time this guy was fat adapted (5-6 weeks) he was using 20g a day. This is important for those of us in ketosis because this is our stating point - we’ve already done the 5-6 week apprenticeship.
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But the interesting thing is that protein isn’t the only substrate for making glucose. We also make glucose from the 10% of a triglyceride that isn’t a lipid - glycerol. And how much of that is available depends on how much body fat we have and how many calories we are using.
We know this guy has roughly 19.5 kgs of body fat to be able to generate 150g of triglyceride/day (which we can calculate given the ratio of body fat to maximal energy using A limit on the energy transfer rate from the human fat store in hypophagia
If he has more body fat and burns more calories - he will use fewer than 20g/day. If he has less fat then he is in a world of hurt - the least of his problems will be he has to burn more protein.
So this hypothetical dude; would need roughly 80g (turnover) + 13g (hypertrophy) + 20g (GNG) = 113g per day.
Everything else he would waste for fuel as empty calories, and every one of those displaces a gram of fat and therefore results in fewer ketones for the brain which will need more glucose … which would use MORE protein.
Eventually when you go down that road of eating protein wasted for energy, you need to eat increasingly more protein.
At some point you will run into the human limit for protein which according to Noli et al Protein poisoning and coastal subsistence Which describes the limits of human protein metabolism as the limit of how much oxygen a human liver can take in.
“the most energy human beings can safely derive from protein sources over an extended period lies in the region of 20-50% of their daily energy needs.”
Let’s say you are on 2000 kCal/day. That limit would be around 250g of Protein.
Just for the sake of completeness I just did Ted Naiman’s calculator and it told me I needed to eat 264g a day of protein. I’m not sure if that is a joke or what … but “Yeah, nah”
Just in case anyone was concerned that all the above is theoretical and I have no ACTUAL case evidence of minimal protein needs. For 2 months before the low Carb Breckenridge conference I ate the Aussie minimum daily intake of protein which for a 52 year old man is 0.84 g/kg LBM … so fo me that was 67g of protein a day.
I’ll bet if you went to that group and asked what would happen to a guy with 80.380 kgs of lean mass who ate 67g of protein a day there would be many dire predictions of lean muscle loss, and skinny fat predictions.
I had a DEXA scan before and after the trial and I went from 80.380kgs lean mass to 80.342kgs, well within the margin of error of the measurement. I also had a knee injury during the event which reduced my cycling from over 150 kms to under 20 kms/week. Which would have had more influence.
So for me, the evidence shows that 67g is adequate. I have no problem with anyone who says that they personally need more, or even people who say they want more. But I would advise anyone getting close to 50% of calories from protein to reach that level gradually to build up their liver enzymes, and be very careful of ammonia intoxication and other symptoms of Rabbit starvation.
. Decreasing your protein intake means increasing your fat intake.