Only if you don’t want to burn up your muscles and you have no body fat (you quit sparing muscle), it (carbs/glucose) probably would be required unless you got lots of fat on-board to burn? Or you eat enough protein to replace the glycogen via gluconeogenesis?
Phinney nor Volek (the researchers in the study your citing) know exactly what’s being used for fuel “hard to say” which they plainly state on the Virta Health website?
One thing is for sure you will never use 100% ketones or fatty acids for fuel there is just not enough of it, it’s just not happening chemically, electrically or mechanically as muscle tissue is designed to store glycogen for energy and to think otherwise is magical thinking?
There is also a paradox to this, being Phinney & Volek are advocates of meat and fat for fuel? Dr. Peter Attia demonstrated in his own N=1’s eating resistant starch is where you truly get BHB from and when your body truly kicks-in butyrate or ketones for fuel because eating only meat and fat kicks-in glucose/glycogen for fuel?
This is also demonstrated in people and cultures who eat high starchy diets; they run faster and longer than anybody in the world and beyond the threshold of even an Olympic athlete?
Why is that? Because they make and produce there own butyrate or ketones for fuel? Rather than constantly depending on an exogenous source (animals)?
And of course the meat and fat advocates are going to throw a temper tantrum jump up and down and throw themselves on the floor and convulse into make believe seizures because technically resistant starch is a CARB…lol