This interests me alot. The whole calories in / calories out theory, sounds good, but I don't think it applies to everyone. I have varied my caloric intake widely, and it sure seems that my metabolism just adapts, and I hold to a set weight almost no matter what I do. I dropped several hundred calories per day, and over a few weeks, lost around 3 lbs. Then with no particular changes in diet, I go right back up to where I was.
So, I add back those 300 or so calories, and I just sit at the same weight. Since, like you, I'm not all bent out of shape over a few pounds of fat, ( although, I'd LIKE to see it gone ) I think I'll stick with plan B, which is to eat as many calories as I can, without gaining weight.
My theory is that if I continue to put on muscle, and my weight stays the same, then I must be losing fat. Right? This makes me wonder, when you say, you put on muscle, but didn't lose any fat or weight... then where did the muscle come from?
I asked in a post some time ago, if my original plan to just add muscle, while keeping my weight constant would cause me to lose fat, and the answer was yes. So, since I don't currently want to drastically alter my diet, I hope that will work. Given time.
Also, on the calories in / calories out thing. I did Atkins about a year and a half ago. I did it to lose weight, and then moved on to a healthier, more balanced diet. I don't promote the Atkins lifestyle. However, many detracters of the Atkins diet, claim that it works because the calorie intake is so low. To me, this is bullshit, because I was eating quite a bit of food, and losing about 5 lbs a week for about the first month. And it was not all water loss, because I was able to keep most of it off, after switching to a healthy diet.
So, there are tricks to losing weight. It's not all about calories in / calories out.