Calorie and resting metabolic rate confusion

I posted this in the exercise forum before I realized ooops, it probably belongs here. Please take a stab at it if you've got any knowledge.

Hi everyone,

I'm hoping there are some people here who have experience who can give me some insight or advice based on either your personal or professional experience with weight loss and fitness.


The Backstory
Have lost 85lbs since January 2010 with the help of lap-band surgery. For the majority of this time I have eaten 1500-1800 calories a day, more on some days certainly, and exercised a good deal. Obviously what I've done has worked up to this point.  Eating only lean protein and vegetables 85% of the time has also been key. I've avoiding grains, sugar, and most carbs other than beans and nuts.

Recently, my band has (finally!) achieved the level of adjustment that I/my doctor seek which means I am satisfied on 1200-1300 calories a day as long as I really do only eat lean protein and vegetables. I can easily eat more if I want to by choosing foods that don't work with the band like ice cream or cookies but the key thing to remember is that if I eat what I'm supposed to, I do not want to and am physically incapable of having more than about 1300 calories a day. What I mean by that is I will end up throwing up if I try to eat more.

I participated in a high tech body composition thing yesterday, similar to a dunk tank but it's a new method using air displacement instead of water displacement and is supposedly just as accurate. I was told my Resting Metabolic rate is 1518 calories per day and that to lose weight I should not be eating less than that.  I imagine the theory is that if you eat less than your RMR your metabolism will slow down or you will break down muscle to get energy? (I dunno? you tell me?)

I still have 70 lbs of fat on my body so I'd like to ideally lose 35 lbs of fat which would leave me with 120 lbs lean body mass and 35 lbs of fat. I know this is not a professional athlete type goal but it's what I want, so please no comments telling me that I should be aiming for something different than what I am. These are the facts, which I'm giving so that you may, if you wish, try to give some advice.

Hopefully the conundrum is now obvious:
If my RMR is 1518 and, accordingly, me just going about my daily life burns about 2200, and on top of that I'm doing exercise like jogging, weight lifting, horseback riding, and rock climbing around 5 times a week (cumulatively) AND I'm eating 1300 calories a day, then why is fat not just falling off of me? I've been at the same weight for the past few weeks, a bit of a plateau I guess, but it ****** me off because scientifically it just doesn't make sense.

Furthermore, I want to understand this "don't eat less than your RMR" thing because interestingly, when I told the guy who was conducting the body composition test that I'd had a lap band, he said "oh, well then this may not apply to you."  So... I don't get it? The fact that I get fuller sooner and stay full longer than a person without a band negates "the rules" of calories in vs. calories out?  It obviously doesn't, and just for those who may not be familiar, the band is not a surgery that changes anything about how the body absorbs nutrients, just makes the stomach "think" it's smaller (this is overly simplified.)

So what's the deal? I personally don't believe that I HAVE TO eat above 1518 a day to lose weight but on the other hand, I'm not losing weight at the rate that would be predicted if any of these measurements were accurate anyway.  Keep in mind, my RMR was measured yesterday after 10 months of restricted calorie eating.  So even if it had slowed down due to the reduced calories, it hasn't slowed down so much that I'd say I believe in "starvation mode."

Sorry for the long post. The whole thing is just very confusing to me. And I think even more so, that people act like it's an exact science and they can tell you just how many calories you should be eating to lose, gain, or maintain weight ... but then they say "oh, nevermind, this rule doesn't apply to you." - it makes me skeptical about the whole thing...and confused and frustrated. 

Thanks for listening.