Since you are already at the lower end of the BMI healthy range, you will probably find it very difficult to lose weight. You will probably need to experiment a bit to see if you can do it safely.

Although you were closer to 140, you are at an age (18 or 19, correct?) where your body is maturing and you may not see that 140 again. That is the lowest "healthy BMI" weight at your height and why worry about it when you are still at the low end? If you are already really active and not losing at 1600, you could try upping cals a bit to see if that helps. It would be better to try to get a good idea of what you are actually burning to make sure you aren't creating too much of a deficit. In your range, a very slow loss (meaning only a small difference/gap between how much eat and how much you burn) is probably best, because it won't be such a shock to your system when you start maintainence (no gap).

If 1700 doesn't work, try 1750, etc. But getting a better idea of your burn would make it easier to see if you have too much of a deficit for someone already so slim.

thank you so much for the response.  I will definitely use your advice.  Thanks!

basically to reiterate what mkculs already said, a slight caloric deficit over a steady, consistent period of time will probably be the best way to achieve your goal.  I wanted to get below 4% body fat a few years ago, and you will not believe how difficult it is to go from 4.0 to 3.9% ....The lower your body fat composition goes, the more difficult it will be to produce the gains that you expect to see...your body simply will not be able to support a large caloric deficit because there physically isn't enough fat to fuel your body...it took me 3 months to drop 0.1% of body fat.

I would guess that you aren't necessarily in the same situation, but it holds true regardless.  The lower you take your body fat percentage, the harder it will be to support a caloric deficit.  Shrink the deficit and you will obviously have a slower burn rate, but then again you aren't trying for "weight loss"....you're headed for "holy crap she looks awesome" ...it's SUPPOSED to be excruciatingly difficult lol

While you may be quite active, perhaps the reason you want to loose more weight is that you have some jiggly things.  Instead of trying to restrict your calorie intake perhaps you should try to do some exercises that target the jiggly things.  Toning up will do wonders for your appearance and get you a LOT closer a lot faster to that "Hoely crap she looks awesome". 

Thanks for both of your replies!! I guess I'll just have to be patient, and keep working hard! Plus I'll focus more on specific exercies to tone up certain areas.  Thanks for the help!

Is is possible that you've "traded" fat for muscle - meaning you've lost fat but gained muscle so the scale doesn't move?  Do your clothes fit differently.  I ask because, in the past - while exercising a lot, I stayed the same weight but went down two sizes due to this phenomenon.  Just thought I'd throw the possibility out there!

Good luck!

emileem you are like my creepy younger self! I'm an emily (I'm assuming you are too from your profile name!) 5'10" and 150 lbs. I'm 24 though. I never really weighed myself much in high school and if I did I've long ago forgotten but I'm pretty sure I came into freshman year around 145lbs. I was active playing ultimate frisbee and didn't drink much so I kept around that weight (i think) for a while... but when I stopped playing frisbee and starting dating someone over 21 i got as high as 173! So to my younger self... don't fall into the same trap! Stay active! I guess the good news is if you follow in my footsteps you'll get your act together and lose the weight by senior year and keep it off. Although another warning, when you cut out the crappy dining hall food make sure you eat enough iron rich stuff or else you'll get anemic like I did. 

Weird post I know but I couldn't help myself! Best of luck to you. I'm sure with patience you'll reach your goal...

Try swimming or pilates. It'll help you tone, which will help get rid of body fat.