This is REALLY interesting. I appreciate all the data you're taking.

I've added a PDF of my latest 24 hour BG curve to my initial post as well as to this post below.  Comments are in the the PDF.

I just noticed that this is the second most popular thread having 529 unique views - second only to a much older thread.
Not many people are posting in it but they sure are reading it!

Glad I'm adding some value to the forum.

I've been trying to reconcile my 4 day weight loss that seems to have lead to a 2% body fat reduction with only a relatively minor increase in activity.    I'm sure some of the weight I lost was water which was released when the glycogen was used and not replaced.  My understanding is that for every gram of glucose or glycogen the body must also store 6 grams of water.  I lost 5 lbs but the caliper measurements said that 2% of that weight or 3.2 lbs was fat. So it looks like I lost 3.2 lbs of fat and 1.8 lbs of water.  The issue is this: to lose one pound of fat you must burn around 3,600 calories. The 3.2 lbs of fat represent 11,500 calories and therein lies the conundrum, where did all those calories go?

The only change I made was to increase my activity by adding a very slow 2 mile jog to my daily routine.  If I remember correctly the body burns about 100 additional calories above baseline per mile when jogging.  This means that I was burning and additional 200 calories per day for a total of 800 additional calories over 4 days. Even if you double this amount it only accounts for about 10% or less of the fat calories I lost, again where did they go?

What do we know: I burned an extra 800-1000 calories over 4 days, ketones rose to level 4+ and stayed there, I lost enough fat to account for 11,500 calories, and I really feel tired.

Here's my best guess on what's going on, and if anyone else has thoughts please chime in.  Most of my body functions are still using glucose - especially the muscles.  We can tell this by the fact that ketone levels don't drop after exercise so they aren't being burned as fuel.

The added exercise is demanding more glucose than I'm supplying in my daily food intake.  I'm eating zero carbs and protein intake is 90-100 grams per day which is the only external source and this is not sufficient to replace the glycogen used by the added jogging activity.  The body has to get the glucose from somewhere - either by sacrificing muscle tissue to get protein to convert to glucose or from fat stores.

I may be sacrificing some muscle tissue but not much as I'm using the majority of my body's muscles in the act of jogging so I don't believe the body will sacrifice tissue from the muscles that are calling for the increased fuel unless there is no other source.  I had a good bit of fat at 14% so I expect this is what was used to create the needed glucose/glycogen for the muscles.

But the body can't really make much glucose out of fat, and my body isn't burning the fat so what gives?  Fat moves in and out of the fat cells as Triglycerides.  A Triglyceride is a Glycerol molecule that binds with 3 fat molecules. The liver can easily convert a glycerol molecule into a glucose molecule.  My theory is that the body is calling for glucose to feed the muscles, the muscles are active so they won't be sacrificed if the body has any other alternative.  There is fat available so it is being called out of storage and the the triglycerides are moving to the liver where the 3 fat molecules are stripped off, converted to ketones and sent to the kidneys and lungs for removal from the body hence level 4+ ketones in my urine.  The remaining glycerol molecule is then converted to glucose and sent to the muscles to be used as fuel.

In other words, very little of the fat that is being pulled out of the fat cells is being used - it's being thrown away.  Only the carrier molecule, glycerol, is useful while my body is running on glucose, so it is the only part of the triglyceride molecule that is being used.  So that is what's happening to the majority of the 11,500 fat calories - their being thrown away at the rate of 3 fat for every 1 glycerol just so the body can free up the glycerol molecules to make glucose! 

If this theory is correct it's clear that this is a stop-gap measure and can't continue very long as it is incredibly inefficient and I have limited stores of fat.  I'm sure the body won't use 100% of my fat so there has to be a limit at which point it will be forced to convert as many systems as possible to ketones and fatty acids as these are in abundance where glucose and the raw materials to make it are scarce.  I expect that as time goes on, if I continue the increased activity, there will come a time where weight loss will stop and ketones in the urine will drop to Trace level as they will now be used as the primary fuel for most body activities. At that point the body will be using 100% of the energy in the triglyceride molecule as the body will be running mostly on fat and ketones but will still need a little glucose for some critical systems.  Hence both the 3 fat molecules as well as the glycerol molecule will be fully metabolized again.

Time will tell if this idea is born out.

Lex

Yes, many outside of this forum are reading this thread. The only reason I used to log on to the MB was to read Lex's proposed experiment. I wondered what happened when it never surfaced and was happy when Nicola mentioned this thread on another forum.

Thanks Lex for doing this. I'm reading along with great interest.