You’re generally correct, except it would take something like a serious endurance athlete in training to burn off that much a day. When you deplete your body of carbs as you describe, there is also a fairly quick drop in water retained in the body. That contributes to, though doesn’t fully cover, why the body appears to be losing so much more wait at the initiation of a fasting, keto or similar diet.
Ketones serve as fuel for the mitochondria to make ATP for fuel in the body without creating the carbon dioxide byproduct when glucose is used.
This process is called the Krebs Cycle or citric acid cycle. It’s an aerobic process that is 7 times more efficient than the anaerobic ATP production in the cytoplasm.
Studies have shown that ketosis reduces hypoxia in the body by decreasing CO2 levels. They found it greatly increased the time free divers could hold their breath under water.
When i first started paleo i lost lotsa weight, when i started IF the next plateau shattered and i lost weight i thought was permanent.
At that point i decided to go for another goal and fasted 24 to 36 hours followed by a giant 5 to 6000 calorie high fat meal over the course of 2 hours and back to fasting. That combined with lots of movement and heavy lifting, body weight exercises, and a 5 to 8 hour hard hike/climb every week got me down to a ripped 160 lbs
I am certain however that the fasting and carb avoidance was 90% of the weight loss
Felt great but life gets in way and its not easy to maintain that lifestyle