I like this article, but I have a question/thought...

Let’s say we have someone on a 20:4 schedule with a TDEE of 2,000 calories/day... And during their 4 hr feeding window, they consume that full 2,000 calories (rather than only eating 1,500 calories so they don’t tank their BMR to 1,500 to match the “calories in”). Regardless of insulin levels, why would their body need to tap into stored fat when they have their daily caloric needs coming in by mouth? Carbs are converted to glucose, proteins to amino acids (and some glucose if it’s a big chunk of protein), and fats to ketones... If glycogen can efficiently run things for roughly 24-48 hrs, and we’re refilling our glycogen stores every day, wouldn’t we have enough glycogen as readily available energy to use for fuel? Why would we need our stored body fat?

Now, WHAT IF, that 20:4 person is eating keto and their glycogen stores are running on E pretty much all the time... Because then, while eating at night, they’re not replenishing those glycogen tanks. HOWEVER, calories don’t magically disappear... If our person ate their 2,000 calorie TDEE (regardless of whether that’s keto, vegan, or McDonalds), where do those calories go and why aren’t they being used for energy/fuel? Even if having low insulin levels opens the gates for body fat to be burned, what happens to the caloric intake they had? If that’s available, that would be used first, but even if it wasn’t being used for some reason (and body fat was the fuel source), then wouldn’t we eventually store those “calories in” as body fat if they’re there and not being used?

Did I miss something in the article? I’m not an alternate day faster, but perhaps a 5:2 or even 4:3 COMBINED WITH KETO would be more in line with what the article is talking about. Because our model could eat their TDEE of 2,000 on 4-5 days out of the week to keep their metabolism at their normal level and then consume 0-500 on their 2-3 fasting days.. So if glycogen levels are non-existent because of their keto diet and their BMR is looking to burn up 2,000 calories that day, then I suppose you’d lose about 1/2 pound per fasting day, yeah?

Maybe I drank too much last night and my brain isn’t functioning correctly today... Because I like the article and brings up some interesting thoughts, but I can’t get over the idea that we could eat our entire TDEE in 1-4 hrs (or whatever your flavor is), and then, when insulin levels drop off from that meal, we’ll start magically burning body fat even though we had just consumed our entire day’s worth of calories. Maybe I should read this thing again and hold off on posting this...