I'm in the same shoes as you are and at a much higher weight. Because of the amount of vegetables and fruit I eat and how carefully I cook, portion, and select my food I'm averaging at 1,100 calories a day. I'm eating very healthy food and am completely satisfied. But as well with my office job and classes my lifestyle is fairly sedentary.
It would be really easy for us to up our caloric intact healthfully with unsaturated fat. Throw olive oil in our cooking or canola oil mayo on our sandwiches. Fat adds up quickly!
Many people say that if you eat too little you can gain weight. That isn't actually the case. But it is possible to slow your progress by slowing down your metabolism with too low of calories. Where does that happen? That is under debate even in the scientific community. The fact is it is different for every person. 1,200 calories comes up a lot but I believe that is because nutritionist say that it is near impossible to get all the nutrients you should have if you are eating less than 1,200 a day. It is true that the less calories we eat the more we should be concerned about eating nutrient packed foods.
Some studies have shown that an individuals metabolism doesn't slow until they start consuming about 50% less calories than what their body is burning. You can -estimate- how much your total burn is through BMR calculators that include activity level. ( BMR / RMR Calculator
) Note these do not take into your body composition! If you have more muscle and less fat than average you will burn more therefore the calorie intake should be higher. As well, studies show that the lower in body fat you are the more likely you will slow your metabolism by eating too little calories.
We want to create deficit but one that definitely doesn't go below 50% of what we burn in a day and for nutrition reasons we should be making sure we are getting what our body needs. Many health experts say that we shouldn't try to lose less than 2 pounds a week. Theoretically you can get a two pound a week loss by creating a deficit of 1,000 calories a day.
There are also claims that if you are eating low calories consistently (the same every day) your body can get used to it and your metabolism slows. All of these extra fat stores are an insurance policy just in case a famine happens and our bodies really aren't interested in us losing them. They see the extra fat as a good thing! Some people will stagger their calories on a specific plan for this reason. (For instance: Mon: 1,200 Tues: 1,400 Wed: 1,200 Thur: 1,600, etc.) I don't do that but I do have a higher calorie (1,600 - 1,800) day every week to remind my body that there is no famine and it doesn't have to hold on to this extra fat.
I wish I had a simple answer for you, but I don't. Most people have different answers on this topic and I'm certainly not in the majority. I also will not advocate eating calories under 1,200 (even if most days I end up doing so). The bottom line is that we need to find that path that is best and healthiest for our own bodies.
Good luck! The important thing is that you keep taking care of your body no matter what you do.