I have been on a low carb (basically zero carb) diet since January 1 and have lost 55 lbs. During that time I have gotten more muscular and defined than at any other time in my life (I am on tren and test) and have made solid gains in strength.
I think whether you do a no carb, carb cycling or carb based diet depends on your preference. As Shortz says the key is to be in a caloric defecit. To know whether you are in a defecit it will help tremendously to weigh or measure everything you eat, and to eat the same things day in and day out. If you are losing 1 to 2 lbs per week, then you are in a defecit. If you are not losing, you may not be in a defecit or you may be too inconsistent in the amount of food you are eating.
What I don't like about carb cycling is it will put you into and out of ketogenesis, which is counterproductive, IMO, unless you are at very low bodyfat to begin with.
And while I have been on a ketogenic diet so long, I have also had cheat days at least once per month, and several days off in a row, every couple of months. Invariably these cheats help me re-start the fat loss process so going forward I am losing fat at a more rapid pace, than just before the cheats.
Whether a diet with carbs is muscle sparing, I cannot say, but I have not lost significant muscle while on my current diet since January.