Initial weight gain

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Starting this month, I have gotten myself back on track with my diet and exercise. I had stepped away from monitoring both the last few months of 2012. My weight loss had stalled and I wasn't loosing anymore. So, this month, I got back to it. I went back to eating the way I had before and doing cardio 5 nights a week. I've been doing good for 2 weeks and this morning I was up a pound. Is it normal for the body to maybe retain fluid after beginning an exercise regimine? I can't remember if this happened to me the last time I started regular exercise.

I know it's not body fat, but it's still discouraging to see a higher number on the scale after 2 weeks of hard work.