ELI5: When insulin is in your blood, fat burning does not happen. The longer you go without an insulin response, the more fat storage is tapped to provide energy. That’s why intermittent fasting works.
Ok so I don’t know the answer to your question. I’ve been doing it for two weeks. But something happened today. I was 5 minutes from my 16 hour fast ending and I felt this insane amount of energy almost borderline euphoria. I am a SAHM and had a free hour so instead of breaking fast I actually did a 30 minute peloton boot camp. I had SO much energy. I just felt amazing. I can’t explain it. So I don’t know what exactly it does but I can tell you I’ve never felt this way before and I am excited to find that feeling again! (Also not that hungry tonight…who am I??)
it allows your body to switch from using the food as energy and switches to energy stores on the body, like body fat, and glycogen stored in the liver. The longer past 16 hours, the more it does its thing. Just from what i understand, im happy with how its going so far. Its not an once overnight thing either, so you still gotta give it time.
Dr. Huberman and Dr. Galpin just put out an amazing podcast episode about how the human body fuels itself. The entire thing is worth a listen but at the 2:13:00 mark, Dr. Galpin explains how your body breaks down fat.
TL;DR - Calories in and calories out ALWAYS matters in terms of losing/gaining body fat.