Am I doing it right?

No, absolutely not! The 1400 is the number you need to maintain health. Any less and you are starving yourself. Eating 700 calories a day, even without exercise is dangerously low. You may lose a little weight at first, but it will mostly be muscle instead of fat. Try never to be under that number and seriously consider eating back at least part of the calories you burn in exercise.

No, not at all, the minimum you should eat is 1200 plus what you burn, so if you burn 400 the minimum you should eat is 1600 (1200+400) but should eat 1800 (1400+400) so you will be safe and lose weight eating between 1600-1800 on days you burn 400 calories, any less may lead to negative health side effects, not to mention cause your body to burn a high % of muscle, instead of fat.

From what I understand, and I'm no expert, consuming only 700 calories for a week or so will cause your body to go into starvation mode and your body will slow down your metabolism to maintain every ounce of weight it can. Once your body responds in this way, even on a day when you "splurge" and consume a huge amount of calories, your body thinks something like, "Oh, we need to keep those calories because who knows when she is going to properly feed us again!" and you end up actually gaining weight, when really a one day splurge should not really be able to significantly impact your overall weight.

Like I said, I'm no expert. I just read about this yesterday when I was researching my own similar question. Perhaps there are others who could explain it better.

Essentially, you need to eat at LEAST 1200 calories per day to avoid going into starvation mode. The only thing I'm not positive about is what happens when you are right at 1200 calories, and then you do some exercise and that brings your next calories under 1200. I wonder if that can also put you into starvation mode. There is much to be learned on this topic I think.

What you are doing now though seems very unhealthy. Please reconsider your approach to weight loss. If you are actually in starvation mode, upping your calories intake would probably increase your weight - initially. However, once your body comes out of starvation mode, I think you'd be able to lose whatever weight you gain and thensome. Overall, I think you will be happier with the results. Best of luck to you!

How is this even a question? Really?

No, it's not healthy AT ALL. Doing that will slow down your metabolism and make it harder to lose weight in the long run. Also when you don't eat enough you don't get the proper nutrition you need, you'll feel lethargic and cranky all the time. There is no way that this would be maintainable in the long run and you would gain back quickly once you started eating normally again.