I joined Crossfit and I love it....It's only for an hour a day and its an intense workout but it helps and works great!
I've read several articles recently, saying that shorter, interval training is better for fat loss than long sustained periods of exercise.
Muscle is much denser than fat, so if you're increasing muscle, it's quite likely you will gain weight. Pay particular attention to how your clothes fit, or take your measurements, periodically, to see if you are gaining muscle.
You might be lossing inches without lossing lbs. the gain in weight may be muscle, not fat.