Just to make sure we are clear, I'm going to talk about it again.

I know if I talk about this enough it will sink in. The number on the scale doesn't mean anything. The only time you should be counting numbers is if you are morbidly obese. Shows like The Biggest Loser make an idea like this so hard to get through to people. They get awarded for dropping pounds and I disagree very much (but by now we all know how much I disagree with that entire show). I very, very rarely use pounds as a way to measure success with my clients. If you are doing everything you should be doing in an exercise program you will gain muscle. Will this show up on a scale? Yes. Is this a bad thing? NO. You are replacing fat with muscle. Is this a good thing? VERY MUCH YES.
Weight fluctuates everyday just by living life. What do you measure instead? Inches. Inches off your waist. Inches of muscle gained on your biceps. Inches are much more accurate than pounds.   
Get. Off. The. Scales.

Thank you have a wonderful day.