If you were chaining prolonged fasts, say 3 to 6 days, between a couple of days OMAD, where OMAD calories would at least meet total usage for the day or even a slight surplus, would this lead to a metabolic slowdown?
Metabolism doesn’t significantly change during fasting. And the reason is simple. Basic thermodynamics. Since people that are fasting have about the same average body temperature and their cardiovascular activity is normal during that time, it means that the amount of heat that they exchange with the environement is about the same, which means their metabolism is pretty much unaltered. If the drop in metabolism was real, then they wouldn’t be able to move, let alone walk at least 5km every day, like I did on my 5 day water fast.