The distinction between “keto” and “low-carb” is arbitrary.
Dr. Phinney considers 50 g/day to be a ketogenic level of carbohydrate intake. It’s what they recommend to their patients at Virta Health. Our recommendation here is stricter, so as to virtually guarantee ketosis, but in truth, a ketogenic diet is any diet that promotes nutritional ketosis.
Dr. Phinney has worked with people who were in ketosis eating as much as 100 g/day of carbohydrate. Carb tolerances are highly individual.
Personally, I use the terms “keto” and “LCHF” interchangeably.