Carb cycling is good. If you can manage it, zero carb is pretty good too. Personally i like carb cycling as it allows for a bit of variety with food. Basically, follow it like this:
2 days Moderate (or high) carb
2 days low carb
3 days NO carb
(the 3 day bit can be whatever, mod, low, no, up to you)
Protein high, healthy fats moderate.
Or go NO carb with a higher carb day every now and again. Keep helathy fats higher with this version. But both diets are good.
Now you said "if i just do cardio", now unless im interpreting this wrong, DO NOT stop weight training. Theres no need to stop, and continuing will help you burn more calories and, with good nutrition, maintain muscle mass.