12 pounds 4 weeks?

I would look into the 30 Day Shred (You can search the forums for some pretty amazing before and after threads). It won't necessarily make the pounds drop off, but it does help with losing inches! Also, for a lot of the posts I've seen on the forums, it can make a pretty significant difference in how you look in just 30 days.

Also, how tall are you? If you're working out I'm thinking that 1200 calories is not going to be enough fuel for your body or to help with weight loss. IMO I would check your TDEE-20% and try and stick with or around that number. Many people (myself included) have had great, sustainable success with eating at their TDEE-20%.

Good luck and don't get discouraged! 12lbs in 4 weeks is 3 pounds a week? 1-2 is usually a good goal for most people...and considering how much or how little you have to lose to be at your goal weight it can be harder to reach a 1-2lbs a week goal, with this in mind, a program that focuses more on body recomp (like 30ds) might give you better results than just calorie restriction alone.

I'm not an expert, just my advice - whatever it's worth

I just started 8 days ago and have already lost 5.8 pounds. I aim for 1200 calories a day but never really get that much. I'm also taking a prescribed appetite suppressant which helps a ton! So I think it is possible...just may not be possible for everyone

This initial loss is most likely due to water weight. 1lb is 3500 calories, you would have to have a deficit of like 20,000 calories in only 8 days to lose 5.8lbs of fat. OP I would just try and be as healthy as possible the next few weeks and take the losses that come, the most important thing is to stay healthy and long term motivated.

Anyway, before a debate starts, I'm out. OP good luck and if you are getting ready for surgery I hope it goes well and you have a fast recovery!