IIRC both combat divers and people with certain kinds of epilepsy benefit from carb free diets as it reduces risk of passing out (for combat divers with rebreathers) and epileptic attacks (for epileptics).
What do you think a 'carb free' diet excludes? What does it include? I'm asking, because I'm genuinely confused by the fact that all plant (veggies, fruits, seeds/grains, all of it) matter contains sugars. Do a lot of folks really sustain themselves on meat alone? Hell, not even my 100lb german shepherd can live on only meat (IIRC carnivores frequently eat stomach contents of herbivores they kill/find to get nutrients [hint: it would include sugars])
I am vegetarian on a very low carb diet. No fruit, no high starch vegetables. It is possible to eat zero added sugar and almost zero natural sugar. As mentioned above your body can synthesize glucose from protein, to the extent that on a keto diet you must be sure not to consume too much protein, lest your body convert it to glucose.
IIRC both combat divers and people with certain kinds of epilepsy benefit from carb free diets as it reduces risk of passing out (for combat divers with rebreathers) and epileptic attacks (for epileptics).