Why would someone gain 20lbs on the Atkins diet instead of losing???

I know that everyones body reacts differently to everything, but why would someone GAIN twenty pounds. I made sure I followed the diet to a T and made sure I was in ketone or kenosis or whatever that is called every day. I followed it for two 2 months and kept my crazy exercise program of 5 times a week with a mix of cardio and weights like one is suppost too, but instead I GAINED weight, and there is NO WAY it is muscle!!! I just don't understand how this could happen? Can anyone offer an possible explination?