How easy is it to lose 12 lbs in 50 days?

At your current weight, not possible. You're already at a healthy weight. Can you lose 12 lbs? Possibly, but it's going to take a looooong time. Your body does not have the fat stores to constitute that kind of loss.

For reference, I'm also 5'2. I started losing weight in June at 211 lbs. It took me 50 days to lose 15.3 lbs, and that was with a pretty aggressive calorie deficit.

Also, 104 lbs at 5'2 will put you into the underweight category, as 105 is the cutoff for healthy.

Really? A lot of people say even people at this height and weight can lose that much. I was quite motivated until I saw this, is 10 pounds not a realistic goal then?

Sure, you can still lose that weight, but it's still going to take a long time because you do not have those fat stores. And it probably won't happen in 50 days. However, even if you lose those 10 lbs, what does it accomplish? Just being on the low end of the BMI scale? Is there a reason you feel you need to lose weight?

Do you want to just look better or have your clothes fit differently? If so, then just look into heavy lifting for body recomposition. That will change your inches, give your body definition, etc. Otherwise, since you're already at a healthy weight, losing 10 lbs (and in 50 days, no less) I would not consider terribly realistic. If you just want to lose 10 lbs for the sake of losing 10 lbs, you should follow MFP's guidelines for losing .5 lbs/week.

Hello everybody . I am 5'2 and 116 pounds. I would like to be 104 pounds in about 50 days, give or take a few days. How difficult would it be?

I'm going to eat 1200 calories a day and I will start going to the gym on Monday and try to work out at least 40 minutes, 3 times a week. What exercises should I do to make it more effective? Is it possible to lose 12 pounds in a month and a half?

Well, 50 days is just a day over 7 weeks, so it would probably be difficult to lose that much in that time. If you really stick to your 1200 calories (or whatever is a healthy deficit for your weight), you’ll likely drop weight. Granted I didn’t start as small as you, but even after getting below 120, I still lose about 1lb/week (some weeks a little more than others and some less).

It’s up to you what you want to weigh as long as you’re staying healthy and not becoming underweight. My only gym advice would be to do cardio (and eat back calories if you can) because if you do weight training you’ll likely lose inches and gain muscle without seeing as much of a difference on the scale. I myself only do cardio because I’m not really looking to get ‘definition’ at this time. A lot of people on MFP feel different and that’s cool too. I say to each their own.