Hi Dr. Feigenbaum,
I just watched your latest YouTube video about macros and would like some clarification.
My understanding is that once protein synthesis is triggered, it can’t be re-triggered again for roughly three hours. What does that imply for any protein that is eaten within that three-hour window? I imagine it’s more complicated than it simply going to waste (meaning not used to rebuild muscle).
It doesn’t contribute to MPS and either is oxidized for fuel, enters futile energy producing cycles, forms pyruvate (and later carbs), or other potential fates.
Fascinating. Seems like this would make strategies like intermittent fasting far from ideal for building muscle. Thanks, Doc.
I think it depends on how you define intermittent. Most people mean a diet where they fast very regularly, for 16 hours a day, everyday. (Not actually intermittent, since it’s a very regular interval). Periodic starvation would maybe be a better name for this diet.
I like to say I’m fasting nearly all the time. 4x/day, each and every day, for about 3-5 hours at a time.
@Jordan – Maybe you should rename your diet “Frequent Fasting” (FF) people would jump on the trend quick. If fasting once a day is good for you, then fast 4 times a day must be incredible.
What if you ate a lot of protein at once or ate a lot of fat with it so digestion is slowed? Could that increase the refractory period?
Or what if it really was 3 hours and you ate more protein after 2 hours, but enough so that it’s not nearly all digested in the next hour. Would that mean that the still digesting protein from the second meal retriggers MPS as soon as possible?
Ok so I did some reading and watched that lecture that people are talking about in other threads and I think I’ve answered my second question. Taking extra protein towards the end of the refractory period won’t trigger MPS again as soon as possible because protein levels need to go down before you can become sensitive again and start another round of MPS. So taking more protein will just keep you desensitised while the original round of MPS continues to taper into oblivion (or just hits nothing after 3 hours, I don’t know).
As for the first question, maybe I should have instead asked if having a meal high in fat will delay the ONSET of MPS and the subsequent 3 hours refractory period.
In the first situation, meh, not really.
In the 2nd situation, you haven’t let the refractory period take place so you just shot yourself in the foot and did not re trigger MPS.
Can someone please just develop some sort of device that tests if muscle protein synthesis is occurring or not? I will pay all the money for it.
It already exists, but it’s impractical and neither you (nor I) can afford it for home use.