Before I start I would like to make clear that I am not a medical adviser nor doctor.
Also by any means I do not pretend to be one. If you seek help for certain medical conditions, please turn to a professional. With that being said lets begin.

Question #1: Why your blood glucose is a bit higher after you lifted weights?

Similar tho what the scientists call the Dawn Phenomenon the body converts some of the stored fat and glycogen in glucose and pushes into the bloodstream. There is nothing to worry about and this is perfectly fine. The 5.0 mark is in the range on what is considered normal blood glucose levels for health individuals. (Between 5.5 and 3.9).

The way to look on it is like the body utilizes or starts to burn the already stored food. Ain’t that awesome? It converts is to energy for the workout. During the Dawn Phenomenon many people experience the exact same thing, but during the earliest hours of the day. In that situation body does the same in order get energy for the whole day.

Typically the people who follow a very low to no carb ketogenic diet often notice their levels stay a bit on the lower side. For example around 4.3 to 4.6 (me including). But by bringing my glucometer with at the gym I noticed my levels stay around the 5.0 mark during my training. For quite a while I was getting a bit nervous about it, but later I found there was nothing to be concerned of. If I use non soaked non hacked rice with my meal on the next day I might experience the Dawn phenomenon.

 

Question #2: How to avoid withdraw and brain fog caused by caffeine during prolonged fasts?

I am not going to lie. I am a coffee lover since I was third grader. During the years I’ve tried many kinds of beans along with fairly big number of brewing methods. Even though I loved the the drink so much for the long period of more than a decade, I was often experiencing pretty unpleasant side effects after drinking it. Some of them similar to the ones explained in the comment, others a lot worse. In fact the ones mentioned were typically coming afterwards some massive anxiety.

Around 2014 I started to look on my diet and everything I was consuming not only from bodybuilding, but also from biohacking perspective. That more or less turned me into a food and coffee snob. Snob or not I readjusted a lot of things including some related to my coffee intake.
Ultimately the side effects were no longer part of my coffee ritual.

Bellow are all of the coffee related adjustments I did.

Types of coffee and methods of brewing 

Because I found about all of the toxins and mold in most of the commercial brands in the grocery stores around the world, I switched to high quality organic coffee beans. Even though I love trying new sorts, I tend to stay away from ones I am not sure about.

I replaced all of the espressos shots with french presses and americano. I noticed when I stick to those ways of brewing there is no crash. Call it bro science or some form of placebo effect, but I also believe that gives me longer and more sustaining caffein release. So instead of amping me so much, the coffee prepared in that manner hits me gently and keeps me up longer.

Even that the americano is technically espresso the additional water makes it more and not that stronger, so i sip on it for quite a while.

For the most part I alternate between brand certified or verified by the Rain forrest alliance and “Agriculture Biologique” , because I am based in Europe. However depends on where you live based you can also order some Caveman or Bulletproof coffees from Amazon. Just do not add the oil and butter when preparing it. In the end of the day we talk about some real fasting.

You can also try to improve your caffeine sensitivity by drinking less on the first and having normal amounts on the second day.

48 hour fasts.

I am no stranger to the 48 hour fasts. Back in 2015 I was eating 5 meals per week for the extended period of 3 months. Nowadays I reintroduced one 48 hour fast. What I changed is that now I do take all of my supplements. The reason is because I feel a lot better.

Make sure to keep your electrolyte balance in check during the whole fasted period. Take enough salt and magnesium and also drink plenty of water. As long as for the water good practice is to always have a bottle around you. I found I do a lot better on spring versus mineral water. While first flushes my whole system the second seems to be too taxing on my kidneys. Typically I aim for a gallon a day. You can use good quality salts such as himalayan rocks or others higher in iodine.
In the end it boils down to finding the things that work best for you.

I hope that makes sense
Yours truly:

Peteonthebeat