Under your calorie goal

Yep, if you're not taking in enough calories to support your daily BMR or your exercise, your body will hold onto all the calories it gets because it's in starvation mode, even if it's just a few hundred under. My suggestion would be to aim to eat what MFP tells you. Before I did that, I was under too and couldn't lose weight to save my life, but now that I'm eating just a bit more, I'm starting to lose again

Yes, especially if your daily calorie goal is low, like 1200. You should always try to meet your calorie goal, that's why it's your goal. If the MFP calculations wanted you to eat less it would give you a lower calorie goal. And you should eat your exercise calories as well.

Not always. If you have a good amout of fiber and protien and feel full and not reaching your calories it is fine. Because that will fill you up. Also you cant eat as much becuase you have been eating less than you use to and your stomach is a lot smaller than it was.

From what I understand, the 1200 calories per day is your MINIMUM you should be intaking so your body doesn't go into starvation mode. As long as you are at that, you should be able to lose weight. I seem to go slightly over every day and am still seeing the pounds drop, so I guess I'm doing it right, then

I'm confused - I've only been using MFP since yesterday but both days I have been under on my calorie goal.

I've been eating a bit less than normal since joining but that is because I want to lose weight, if I reached my calorie goal then I'd be eating the amount I used to eat?

I have lost 2 pounds though since yesterday, so I'm not worrying about it too much )

I think it completely and utterly depends.

It depends on how much you are trying to lose, where you are in the process, how much of a deficit you've built in, how much you exercise, how active you are outside of exercise, hold old you are, if you are a man or a woman, and a host of other factors.

The first thing to keep in mind is that all the numbers on MFP are estimates. The amount of calories it thinks it takes you to maintain is based on what it thinks your BMR is. If it gets the BMR wrong, then everything after that is wrong, too.

If it puts your BMR too high, it's going to tell you to eat an enormous amount of calories and, if you listen, you may not lose at all. When I first started losing weight, that happened to me. I know what I needed to maintain my then weight because I had been stable at that weight for a few years. I knew that eating 1800 calories a day would give me a 500 calorie deficit and have me losing 1 pound a week on average. But MFP told me that 1800 calories was a 1000 calorie deficit and I should be losing 2 pounds a week on it. If I had gone by MFP's numbers and put my goal calories at 2300 to lose 1 pound a week, I wouldn't have lost ANYTHING.

OTOH, now that I'm at goal, MFP is telling me my BMR Is 1050-ish. I happen to know (from a variety of more reliable sources) that my BMR is closer to 1250. If I listened to MFP now, I would be skin and bones because it thinks I should eat 1600 calories on days I burn 2000!

This is why I think people should use MFP to get in the ballpark but then you have to adjust to reality. You can't take these numbers as gospel.

As for the general recommendations, they are based on a lot of assumptions. Generally we're advised not to go under 1200 calories a day *consumed* without being under a doctor's supervision. 800 calories a day is generally considered the minimal amount of calories you can eat without damaging yourself (your heart in particular) but that sort of VLCD is only recommended if you are under a doctor's care and getting regular monitoring and taking lots of supplements.

Even so, I have trouble believing that ONE number works for everyone. I know the 1200 calorie recommendation assumes moderate exercise. So, if you are someone who works out intensely for at least an hour a day, well, 1200 just isn't going to be enough. Using 1200 net instead of 1200 consumed can help but that isn't really what the recommendation is based on. It also assumes you are a woman and not very tall/big. If I were an active guy of 6' or so, there's no way I'd try to live on 1200 calories, net or otherwise without talking to my doctor first. But for us short, middle-aged women, sometimes 1200 calories is maintenance calories! So, you have to go under or you aren't going to lose weight.

Also, most of what is posted on this site about starvation mode is a myth. Here's a good article on it:

http://www.weightwatchers.com/util/art/index_art.aspx?tabnum=1&art_id=35501

Obviously you can't avoid the laws of thermodynamics, to take in less calories then you burn and to not loose weight would make you a perpetual motion machine. This is why a "California Diet" can technically work...

Still, starvation mode is not good. Your body will get slower and more efficient, rapidly dropping the amount of calories it needs to get through its day. You may feel active (because you are tired) but you will be inching closer to a sedentary lifestyle without realizing it. When you do finally eat more calories, your body will immediately store them as fat.

@Hannah_2507 I do the same thing with my exercise calories, but 1200 cal a day is pretty low. Just make sure, if you don't already, to calculate your BMR and always eat enough (including eating back workout calories) to be above that number