Protein absorption - help me understand

80%/20% plant fats/animal protein. The plant fats come from avocado, tree nuts, EVOO, dark chocolate. Rest is large qty of above ground vestiges like asparagus, salads, mushrooms, tomatoes, peppers, etc…very low carb vegetables. I do my daily exercise just before dinner. TBH, I’ve never actually done the calorie math, but MAX 1500 calories/day. My ketogenic/OMAD has most definitely slowed down my metabolism immensely (my thyroid panel confirms this, low T3; my brain “thinks” I am starving but I am clearly NOT, so it shuts things down). I can still maintain weight with a vigorous daily exercise with apparently lower calories. It’s really NOT that hard to eat my single 1500 calorie meal in one sitting…the foods are INTENSELY calorie/nutrient dense; there’s no filler. Going keto is easy…it’s the OMAD that’s hard. Having a hunger signal all day, but I’ve completely learned how to ignore it. I sure hope this lower revving is a slower mTOR AUC.

Sorry, yes, for a 58 yo male. I use to do MORE CRF per day, 20-30 mins Zone 2/3, but I took duration down some, opting for the benefits of a higher Zone signal vs lower bpm/duration. There is much literature showing that the neuro/myokine benefits are produced at the higher BPM levels. Beyond muscle/CRF/mito fitness, I exercise daily purely for the neurocognitive signalling benefits (BDNF, etc). When you engage in vigorous exercise (BOTH RET and aerobic), the liver and muscles release a myriad of endogenous signalling molecules. So I am choosing to bathe in them (and ketones) daily.


Many people say caloric restriction makes them feel bad, maybe from testosterone levels plummeting, Bryan Johnson takes testosterone (Maybe even estrogen or other hormones critical in males at a certain range) How has that been in your experience, do you measure T levels?

Not sure, perhaps having a relatively constant ghrelin signal cannot be too much fun psychologically; humans are conditioned to be in constant satiation, otherwise, time to reach for the fridge! You’ve heard of the term “hangry”. I’ve heard (and felt myself) feelings of coldness…I will often get tingling finger sensation (and overall very strong sense of coldness), especially in the winter, if my glucose gets too low. I don’t think testosterone is involved much in the CR/mood axis, at least not extending to psychological impact. I felt the same before/after TRT (started midway) whilst on keto/OMAD.

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Nothing worth doing is easy. That’s the challenge…to shift your mind/body to a different and hopefully better homeostasis. It’s really mind over matter…humans can pretty much do anything they put their minds to with sufficient willpower/resolve. If you believe in hormesis (which I do), then this constant “stress” signal is causing your body to heal/repair/strengthen itself for superior resiliency…autophagy/longevity?! You are triggering ancestral survival pathways when you put the body in a cyclic state of hormesis. Of course, you don’t want to feel bad or under psychological stress, so it’s all n=1.

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Thanks for the info. I still there are a couple ares that are not totally clear.

  1. AA’s don’t go to the liver because they are in excess, they go there as first pass effect from the intestines.
  2. The basic question of the recommended amount of protein intake by most experts clearly overwhelms the body’s ability to absorb that amount of protein remains unanswered.

Btw, since you do omad, what do you think of expert opinion that omad results in muscle loss?

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7yrs in…completely debunked! You can manipulate nutrition, time restricted feeding, and exercise an infinite number of ways. The mirror and the scale is all you need, adjust accordingly. I have only gained muscle strength/mass, but that’s largely my resistance exercise, not diet or time restricted feeding…so despite my OMAD.

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Yes that’s basically true, more protein than needed to maintain nitrogen balance. The rates of obesity, driven by excess nutrition, especially proteins, globally confirms this premise. Just take a vacation to an all inclusive resort…scientific excess protein experiment live.

The “optimum” is all n=1 depending on your objectives, one can manipulate infinite ways. This is the problem with these RDA standards/targets, they are an average population level.

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Lots of intelligent and interesting posts here but the question regarding absorption rate and it’s implication to protein serving size and frequency still remains.

Let me reframe a different way. Is there any difference between consuming 80g of beef protein (OMAD?) and consuming two servings of 40g of beef protein with a 4 hour interval between? I contend that there is not because it would take over 8 (EIGHT!) hours to absorb the first.

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Please explicitly frame your exact physiological “difference” criteria? Exercising, what level of MET if exercising, rested, OMAD, rMBR (resting metabolic rate), MPS, mTOR AUC, Gluconeogensis, eating with what other foods and their specific nutrient profile/qty.

In a rested state, we already know 80g of beef protein in one bolus, there will be significant EAA still in the bloodstream at 8hrs by the fact there are still elevated levels of leucine at 5 hrs at only 30g beef protein (74 kg young male reference above paper milk vs beef). And a significant amount (depending on metabolic needs, especially rested) will be converted to glucose, and if in excess, into fat stores. Even if you take 0.4g/kg base needs (the above milk vs beef study, 30g/74kg = 0.4g/kg), 80g protein would be the base needs of a 200kg person. Clearly, excess. How long would that take to clear out, maybe days!

We also know that even 40g beef protein, there will be likely still be EAA in the bloodstream at 5hrs. What is happening after those EAA leave the bloodstream…they are taken intracellularly to be processed by mito for various structural/homeostatic needs, but there is a KINETICS to this process too…taking say many many hours more. So what levers of the physiological response are you wanting to understand/manipulate?

I don’t have this exact scientific physiological answer, but for the average person, it’s “probably metabolically better” to take 40g split over 2 sessions with 4hrs in between. But your singular scenario is quite a large beef protein challenge over such a short period of time before next bolus, that it MAY INDEED NOT matter at all!!

At some point, with sufficiently small beef protein intakes, metabolically it would likely tease out the separation of the ingesting intervals.

If one were doing massive MET’s, then I’d say the separation between a singular 80g post work out bolus, vs 40 g post workout, and 40 g 4 hours later might elicit a noticeable metabolic differential signal.

158g of beef (30 g protein) as per above milk vs beef paper, is about 455 calories. So scaling to your 80g beef protein example (421g of beef), this would be 1200 calories.

Someone doing very high MET with high skeletal lean body mass/muscle, would surely consume the bloodstream EAA at a far higher rate than sedentary. The leucine/time curve post workout would look very much different, flatter, returning to baseline quicker. But then, a massive MET workout would generate massive mTOR on top.

So in this scenario, I still think it’s better to split the 80g into 40g, then 40g 4 hrs later. But again, we need to agree on “better”.

It seems that small amounts of animal protein, spread across several intervals leads to larger net MPS gains, per the leucine balance dynamic. It might not matter at all with your singular “beef protein challenge”.

Whenever I’ve had food poisoning, I “sense” my stomach stops working many hours ,(6 to 18) before I “bring it back up”. I don’t think that indicates much about normal digestion.

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I call bullshit on this quote. This makes no sense. Sure much of the protein will undergo gluconeogenesis if you haven’t eaten for long and eat some pure protein on a fasting stomach with nothing else. However, if you eat protein as part of a meal with some carbs then gluconeogenesis will be suppressed and the protein will have a chance to be put to good use. This is why if you eat a large meal with lots of carbs the carbs will give you plenty of glucose for many hours and there will be no need to activate gluconeogenesis and your body can use most of the protein for protein synthesis. So I disagree that you absolutely need more than 20 grams.

Also one minute earlier in the video, Peter said that eating twice a day while getting 160 g of protein daily won’t work because you can’t put 80 g of protein to work. Well sure, you won’t use all the 80 g for protein synthesis, but that doesn’t matter. You will still get lots of protein synthesis and it’s not going to significantly be less than if you ate say 40 g four times a day instead of 80 g twice a day. This is clear from anecdotal evidence in people doing intermittent fasting. BTW, in my twenties I used to eat 150 g of protein daily divided in two meals daily. It worked just as well as eating smaller amounts more often daily. The same is true for tons of other people.

While I didn’t bother watching the video, the comments I have seen are disappointing and reduce my trust in Peter Attia.

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Here’s more info on this question. This podcast (not mine) also provides a clue to a path to minimum necessary protein vs maximum usable protein.

Eating more protein than the minimum eliminates or reduces a need for protein selection for quality, spreading intake throughout the day, but may come with higher than necessary mTOR activation.


It’s all so confusing and there was a new study out recently that suggests we can absorb more in one sitting at once… but take anything I say with a grain of salt because I have no memory for this sort of thing.

Attia had an updated protein podcast out within the last week or two, fwiw.

I’m 100% plant based and won’t alter that, but it is confusing if I should be taking protein shakes to get really high intake for muscle, or do I go for the minimum RDA which might be better for longevity (excluding muscle needs)… and I love grazing most of my food (definitely not all) over an aprox 4 hour window, but then get confused because they say you should get x amount of protein spread out. (My small window is not for longevity but just how i like to eat… and my overall window is usually 9-12 hours of eating.

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@beth. The podcast episode I linked speaks to your questions. It would be worth your time.

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I generally really like and respect Hill, but where I am unsure about how deep to follow him is I know he encourages people to take supplements that he has a financial stake in, but he doesn’t disclose this stake. (I have zero problem with people cashing in, but when presented as being helpful and not making money, I then have to question everything that comes out of their mouth).

I frankly even looked to hire him at one time, I think he has a lot of great things to say.

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I only pay attention to the guest. I think Hill does a good job of not inserting his views but still it is the guest’s expertise that you should listen to in this episode I linked.


Joseph, I finally watched that podcast, and it was, as you suggested, very helpful!! I really liked that guest.

As an aging woman who is on the small side, my take away is I probably should incorporate protein shakes because it’s hard for me to eat enough to offset the protein quality on my 100% plant based diet.

It sounds like, as a woman, even if I ate an omnivore diet, I might still need some supplementation to maintain/build muscle at 60 and beyond. This is a contrast to a bigger person who eats enough calories and doesn’t really need to worry about much.


A bit more on minimum protein per day… and protein needed for the person doing muscle resistance workouts :muscle:.

No surprise… I am a huge post workout advocate for steak… worked out at 1pm had a nice sirloin steak at 3pm.


I don’t think the following recent study has been brought to the forum. The title says it all. My first meal of the day generally 1pm consists of a variety of plant and animal proteins. Over 100 grams I estimate. I never bought into the view that over 25-40 grams was useless for an anabolic response.

PIIS2666379123005402.pdf (5.8 MB)