It's a function of metabolism. Human physiology is adept at storing fat. You have thyroid, TSH, ghrelin, etc., all play a role. One of the upsides of IF (5/2) is that you don't downreg your thyroid. People with ridiculously fast metabolisms can have crazy transit times (motility) but then they are not storing excess calories like your fatties. Your body will utilize what it can and store the rest. Isolating kcals to a single meal boosts ghrelin which increases storage as well as hunger.
I believe that if you are fasting and then consume 3 Big Macs, you body will certainly reward you with a mud like shit but I doubt all excessive calories will simply pass through. The body is trained to process the food and store what is excessive, it only will pass on the waste by products, IMHO.
Interestingly, in the second video, Mattson suggests that vigorous exercise may have a similar effect on the body as does intermittent fasting. And so, I'm hoping that my workout regimen will compensate for my 10-hour feeding window. Although, I'm thinking about whittling it down to 9 hours and see how it goes. (Damn these guilt-invoking threads!)
A friend of mine went to a Fasting Retreat in Russia. 24 days of no food at all. Only water (maybe some supplements). And enemas 3 times a day. He lost 50 lbs (he was 240 at the start). According to his experience - every single thing improved, markedly. From sleep to skin to cognition to bloodwork.
Laces, that was a catcher's camp. The weight loss was just a perk. Are you going back once you fully recover?
There is a Netflix documentary about that place or one like it in a discussion about fasting and keto diets.
sorry had to.go look it up as I forgot. The Science of Fasting on Netflix. First part of the doc is about a fasting center in Russia.
Is anyone fasting and doing HIT resistance training? I ask as both trigger autophagy and wonder if there is such a thing as too much autophagy?