Fasted Workout and Blood Glucose
I did an experiment last weekend with a two day fast. I used the Precision xtra to monitor and trend blood glucose and ketone levels at about every four hours. Prior to the fast I was not in ketosis. On the first day of my fast, I went on a 3 hour walk to burn of any stored glycogen. My fasting morning glucose was ~ 70 upon waking, and was about the same after walking. My ketone level was about 0.5 mmol upon waking. Later that evening I went in to go workout with my trainer doing heavy lifts. I noticed that my blood glucose after the workout was up to about ~120, and my ketones almost 0. Does anyone know why my blood glucose increased during my workout? I know the liver can create glucose from liver glycogen to help with creating ATP during a workout, but what if the liver is already depleted of glycogen? I heard a talk by Peter Attia on this, but he didn't dive into what was going on here. Any insight on this would be great. Feel free to get nerdy with the answer if you need to.
Other info. I'm 29, male, 165 lbs, 18% body fat, no diabetic issues.