This is a few years back, wanted to see what happened. Had to take the GF out for a nice dinner, so I had some steak, fish and booze. Ketosis held strong.
Your strips stayed black! Very nice.
Last year I did a 7 day fast and I scarfed down a buttload of sushi, which as you know contains carbs from the rice. I remember believing that it would probably take me over a week to get back into ketosis (I remember being into keto and people saying it would take weeks to get “keto adapted”), but after 24 hours of fasting and some walking I was back in the deep purple.
As you’ve witnessed, the brilliance of fasting is that you can easily deplete your glycogen stores and stay in fat burning mode. Even with a carb load, most of those carbs will get prioritized for immediate activity and anything that gets stored can be quickly burned through.