do you have to eat tha calories back?

You can choose. 1lb is about 3500 calories.. so if burn that, you lose 1lb.. but, if you eat it back, you still get the benefit of your burn, but you'll lose the lbs much more slowly. My goal is to NOT eat back my workout calories, to lose weight quicker, but sometimes, when you do something with a heavy burn, like swimming, your body NEEDS some of those extra calories, or so I think. Good luck!

UPDATE:
Hey guys, I didn't know about the BMR stuff, so now it makes sense.. my BMR is 1100, so I think I'm safe letting a hundred or so calories go

I recommend you eat your calories back. If you think about it. You are now eating 1100 calories a day and you are burning say 900. That means you are only eating 200 calories for the whole day! It's not enough food for you. I eat back my calories. Good luck!

Definitely eat those exercise calories back!! You're eating WAY too little. You should never eat less than your BMR. A good way to gauge how much you should eat is to figure out your TDEE then -20%. I was only eating 1200 calories (and eating back half of my exercise calories) and my weight loss stalled (even gained one week). I did a LOT of research and found out I was eating way too little. I upped my calories, eat back all of my exercise calories, and I'm losing very nicely now. By eating too few calories, you will not only stall your weight loss, you will absolutely mess up your metabolism and your hormones. For your own healthy, eat more! Your body will thank you and not hold on to your fat for survival.

Yep I always do and it works.... Don't starve yourself . I've lost 100 lbs trust me

I've only been using those "extra" calories if needed. Um, like the other day, I worked out specifically so I could eat a Snickers bar that I otherwise wouldn't have had the calories for.

I figure it's ok because before MFP I would've not exercised and eaten the Snickers anyway.

Lol. I do the same thing. I'll bust my butt doing circuit training with my trainer so I can have pizza and beer that night.

Going VLCD (which is what you're doing seeing as you're netting 100-200 calories a day) is a very drastic move that should really only be done under medical supervision. It's an extremely harsh 'quick fix' method - great if your doctor is telling you need to drop 50lbs before he'll do an operation, but bad if your serious about weight loss. Go lower than your BMR and your metabolic rate can slow up to 30% whilst you're eating that low because your body is desperately trying to survive a famine. Get to your goal weight and unless you're going to be busting your backside in a gym every day, chances are the weight will pile back on again as your body will now be grabbing every last drop of energy from your food and storing it away like crazy.

MFP already gives 1,200 as a minimum calorie goal...and even then only if you tell it you want to lose 2lbs a week and are sedentary. If you go that low you are supposed to eat the calories it adds to your daily goal when you've exercised.

i want 2 lose a lot of weight, cuz i hav a butt, and i look like a girl frum the back. and my stomach sticks out. :sad: i've been doin this for lyke 1 week with this account an lost 2.6 poundz. so its not like i'm losin 8 per week. i jus wanna lose it fast

You're not going to lose weight off your *kitten* alone - weight loss doesn't work that way. Plus, if that's you in the profile photo it doesn't look like you need to lose weight at all....if you're not happy with your body try redefining it with strength training.

my doctor didnt tell me anything. i decided myself. if i lose 10 poundz an i like how my butt lookz, i'll stop

It's probably not going to look any different whatsoever - 10lbs is barely any weight to have to lose. Again, if you want to redefine your body shape when you've got that little to lose, do some strength training.