From my learning experience with this which has been very brief:
Learning how to really burn fat by paying careful attention to glucose numbers is the secret to this and maintaining (sustainability) the full keto adaption is even more difficult in the midst of the damage from previous dietary habits involving high levels of glucose which damaged the body to begin with. I can tell you right now a lot of the information out their even from the experts that have PhD’s, doctorates or dietician degrees behind their name are flat out wrong and have no special access to secret information on the subject because they too are as confused as we are as to what is or what is not the better diet and have not had the unbridled time (time is money) to really delve into the deeper inner esoteric working of what is really going on with this so you only get a scattered version of the picture!
Insulin spiking, eating time and physical exertion levels must be synchronized in a way that has to play catch up (so fat does not get blocked from being burned or stored) along with the circaidian hooks; literally sun up to sun down, it is still a mystery to me why the literal positions of the lunar and solar bodies matters so much to weight loss, but it does, and at the same time makes no logical sense as to why it works like this, it does not matter if your a night owl who does not follow the circadian clock of solar and lunar body positions and tries to reverse it, it will not work when trying to burn fat!
When you look at the history[1] of what is defined as a ‘ketogenic diet’ and how we define a certain substance called “ketones” which are just by-products of oxidized fat cells, but what the heck is that? Why is that happening? We know they kill cancer so far!
If you really do look at the history of the ketogenic diet, the very definition KETOSIS is interchangeable with FASTING, they ARE ONE AND THE SAME-THING, it is not defined as eating high fat, it is defined as “FASTING.” That is a far cry from eating high fat (although the body can handle it quite well). The fat is only to satiate the body prior to being in a FASTING STATE. Eating fat in the beginning is TRAINING the body and liver to utilize fat for energy, to burn fat but is not sustainable by itself if their is no fat to burn (other than eating fat) anymore AND THEREIN LIES THE PROBLEM!
The problem comes from eating too much of the wrong food within an allotted period of time (fat storing process) in the circaidian cycle thus causing a progressive chain reaction that breaks down all defenses eventually if their is nothing to break the cycle of progression unless fasting is utilized!
So if the body has enough sugar energy to sustain it, it also must be intro-convertable and switch to ketones for energy at some point so it has an even metabolic switching processes to give each a break from the other, if no break is given; one from the other, then we are talking about sustainability problems by trying to choose between the two as one being correct over the other.
The problem is with our thinking as one being mutually exclusive to or over the other when they are not! If you put too much energy into a thing, it is going to explode without any lever or alternate route to relieve some of the pressure! i.e. Intermitent Synchronization, Synergistic Symbiosis and Equilibrium are the key to this!
With my own body I am noticing I can add more sugar and carbs to my diet and it is not effecting my Ketosis at all which is really amazing too me!