The view that more protein is better generally prevails, though some people advocate occasional protein fasts (for example, and recently, Mark Sisson, a former advocate of high-protein pretty much all the time). Protein Fasts supposedly help with, among other things, protein absorption on high protein days and with the autophagy/recycling of proteins (thereby perhaps mitigating the risks of a high protein diet)...
By protein fasting once a week, you are essentially allowing your body a day to use its digestive machinery to perform self-maintenance. This is because dramatically lowering your protein intake once a week induces autophagy (What Is Bulletproof Protein Fasting)
I'm wondering, though, if protein fasts are necessary on an intermittent dieting regime? I think (but can't find them again) that studies using nitrogen balance suggest that by morning most people have depleted their amino acids (particularly if they aren't enjoying casein before bed).
Intermittent fasting imposes periods of zero protein and zero food, giving your body a dose of autophagy and a respite from mTOR/IGF-1 activation, and likely making higher protein intakes on feeding days safer
Will resistance training in the morning while fasted, and staying in a fasted state until 10 am or even 12 pm (similar to the Lean gains early morning routine), provide enough protein recycling that protein fasting (say, once a week) isn't really necessary?
Or is it still beneficial to do a whole day protein fast regularly (aiming to get under 15g or 25g ...)?
NOTE: By a protein fast I mean still eating other macronutrients but avoiding food that is more than about 2% protein by weight.
FURTHER NOTE: To make the 'Physical Fitness' context of the question clear - I'm pondering if low protein days are necessary in an intermittent fasting regime because:
- they could increase physical fitness (better protein absorption, healthier mitochondria/more energy, autophagy/general health, this being the main benefit)
or conversely they could
- limit recovery (through, for example, extended time without proteins for recovery, particularly for people who train often and fast [a little] often).
FURTHER NOTE: To put the question differently I could ask, "How much autophagy and protein recycling occurs during intermittent fasting, particularly in the post-workout fasted hours at T = 14h to 17h, compared to 24-40 hours of low-protein (25 g or even less) and minimal exercise?"