Newbie...help with numbers, please...

How much do you weight? How high did you set your weekly loss goal? Do you weight all your food on a scale?

I guess 2 lbs per week is far too agressive. You don't have much to lose so set it to 1/2 to 1lbs per week. And seriously, get your expectations straight: how long did it take to gain this excess weight? 15 lbs in 2.5 months sounds more like a cash diet, which is not sustainable. Thus eat properly. Your base metabolic rate, thus the energy your body needs just to function if you were in a coma is already at 1600-something. You should not be eating much below this, if at all. If you eat around 1690 or so you should still lose over 2 pounds per month.

At your height and current weight, it doesn't seem logical to try to lose 2 lbs/week. It is easier to lose when you have lots to, but as you get closer to your healthy range it gets harder. You should calculate your BMR and TDEE and find a caloric range based on those numbers. Here's a link to calculate them:
http://iifym.com/bmr-calculator/
http://iifym.com/tdee-calculator/

She's lost 15 pounds in 2 months, I don't think she's having an issue with over estimating her food logging, especially when she's only trying for 1000 cals a day.

I need to lose 65lbs and im on 1200 a day, 1000 calories is far too low, you should definitely be eating more. What i do to lose weight is eat my 1200 calorie allowance and then eat back my exercise calories, so if i burn 300 going for a jog, that means i have 300 extra calories that i can eat

There are different methods of calculating it. Use a method that does not use body fat. Use this: http://scoobysworkshop.com/accurate-calorie-calculator/ and skip step 7-10. Your BMI will show below. Btw, a 20% calorie reduction might be too low for your weight and how little you want to lose.

alskarani wrote:

5'11", I weigh 186. I set my goal as 2 lbs per week. I want to be 145. I do weigh my food on a scale. Honestly, I've been afraid to eat more than 1000 calories, but it hasn't really been working for me. In the past 2.5 months, I've probably only lost 15 lbs. I don't understand why I'm not losing more?

Going by BMI, a healthy weight for your height is 135 - 175.
So you're already really close to a healthy weight. That's why you're losing slowly.
It's not reasonable for you to expect to lose 2 lb a week. 0.5 lb per week could be doable.
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I just want to get there as fast as possible!

That's not healthy, not sustainable, and since you say you're "afraid to eat more than 1000 calories" I'd strongly suggest you talk with your doctor & get a referral to a counselor who can help you straighten out this disordered thinking.
You could also look into increasing your weightlifting so that you'll get toned & strong & look amazing. You'll lose inches, even if you don't lose pounds.
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According to this calculator, which shows BMI, maintenance calories, and servings of food groups, at 186 your BMI is 26 and being inactive you should have just over 1800 cal/day.
At 155, it's 21.7 and you'd need 1680 to maintain that weight.
To lose 0.5 lb per week, cut 250 cal/day, or 1430.
Ignore exercise calories. (Exercise, because it's good for you, but don't eat them back.)
Don't go below 1200 actual (not net) calories unless your doctor says it's OK. You're far too tall for that to be a healthy calorie level for you.
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Probably you're not eating as little as you think. If you were, you'd be losing weight like crazy, unhealthfully fast, probably feeling sluggish, ill, tired... in short, it's not a good idea.
I'm about 5'10", depending on when I'm measured, and my calorie goal is 1400.
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Here's a newbie help post with links to lots of helpful info, including sexypants (go read it, then come back here), realistic goal setting (weight, calories, macros), accurate logging, motivation/encouragement...
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I tried to calculate my BMR, but I don't know my body fat percentage, and don't know how I can find that out

For BMR, on the blue bar at the top of the page click on "apps", then on the bar under that click on "BMR".
http://www.myfitnesspal.com/tools/bmr-calculator
Here's a body fat calculator; it uses several body measurements. That's not related to BMR.
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Your base metabolic rate, thus the energy your body needs just to function if you were in a coma is already at 1600-something. You should not be eating much below this, if at all.

This is false. I've been eating several hundred calories below my BMR for over a year (well, except for a few days) and I'm fine. My doctors are happy with my health & progress. And I generally don't eat back my exercise calories. (On average, maybe 1/3 of the time, and then only a couple hundred, and I'm trying to cut back on both of those.)
My dietician & doctor (endocrinologist in charge of the weight loss clinic at the hospital) said not to.
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alskarani wrote:

Basal Metabolic Rate (BMR): 1672
Daily calories to maintain weight (TDEE): 2299
Daily calories based on goal in step 6: 1839

But then why am I gaining on 1000 a day? With light exercise? I'm really scared to eat 1800 calories in a day! (This is 20% reduction). It seems so high! Why would MFP have me at 1200 if that weren't what I should do?

1 - Ignore exercise calories / TDEE / net calories.

2 - You're probably not eating 1000 calories per day. Go read sexypants, read the links about accurate weighing/logging of food. If you open your diary, we could probably point out places where you could improve or tighten up your logging, measurements, data choices, etc.

3 - MFP is only a calculator. It works on the info you've given it. If you've asked it to tell you how little to eat to lose 2 lb per week, that's what it will do, but it won't tell you less than 1200.

4 - 0.2 lb is not a gain, it's a fluctuation. If you drink a bottle of water, you've gained 1 lb. If you pee, you've probably lost 0.5 lb. Have dinner, you're probably up at least a pound. Since you're freaked out by minor daily fluctuations, only weigh yourself once a week. Write it on the calendar so you can look back several weeks to see the trend.

5 - Go see a counselor. You're freaking out over minor things, you're scared to eat a normal amount of food. Even on the days I've gone 1000 over my calories & not exercised, the 5-week projection says I'd maintain weight. Not gain, maintain. Just a pause in reaching my goal, not a step back.