No, you definitely cannot, as it contains a considerable amount of sugar and carbs. Even a small 12-ounce can of regular soda contains over 40 grams of carbs, making them very unhealthy. To top it off, they also have an insane amount of sugar in them, thanks to all the artificial sweeteners added to them. Since many of these sodas also contain many artificial preservatives and flavors, they tend to be very unhealthy. You should avoid them entirely if you can, and you will undoubtedly need to do so if you want to stay in ketosis.