Glucose testing is key, if you run on fat (LCHF diet) the lower the better. if your running on carbs, then the lowest amount of high quality carbs that work for you and don't raise your bloods.
I get about 150g a day, but all whole wheat, none bread/potato/pasta type carbs so (whole grains, lentils beans and some lower sugar fruit).
I do allot of exercise and simply cannot do it without the carbs so it works for me and my bloods are fine with it.