Is this another Fad?

Really interesting. I first I thought it was crap because when you are in ketosis, you discard a lot of the keytones via urine. But I did some additional research. This paragraph was interesting:

Beta-hydroxybutyrate (BHB) – After being keto-adapted for a couple of weeks, you will begin to convert the acetoacetate into BHB as it is a much more efficient source of fuel (it undergoes an additional chemical reaction that provides more energy for the cell than acetoacetate). In general, studies show that the body and brain prefer using BHB and acetoacetate for energy because the cells can use it 70% more efficiently than glucose.

However, I don't think ketones should be considered a macro. IT is the end result of bodily processes and I wonder what feedback the body gets from being artificially given higher levels of keytones...

I just eat food and workout. Maybe if I were in the top 10 in the world I would obsess about things that can save me 3 seconds in an IM.

It's unreasonable to live life on "diets" like this for the every day age grouper.
As mentioned before, maybe if you're a world class athlete and you have time to cycle your food like that and be VERY specific ALL THE TIME, it might be worth it.
I hate the word "diet" anyways... people diet to lose weight, lose weight, and then gravitate back to how they were eating before because the "diet life" was not sustainable.
I also hate the "hacks" approach to a quick fix that falls apart long term.

Also mentioned before, eat real whole foods, train, sleep and you'll be fine. Find a lifestyle and eating habit that works indefinitely that you can sustain without suffering... and if going Keto works for you forever, then knock it out.