The question in the title of your post and the question in your post itself are very different.
"Do you lose if you eat less than 1200 calories?" -- yes, I do. I lose if I eat fewer than about 1350 calories, in fact. Anything under that, and my weight decreases. It's unhealthy to eat fewer than 1200 calories/day, but when I've done it -- and I have -- I lost weight dramatically. I'm not willing to do that anymore, the benefits don't outweigh the costs.
"Should I add more calories" -- yes -- if you aren't getting 1200 / day, you are undernourished most likely. It would be a good idea to get at least 1200 as a minimum. It's not hard to do -- just use full fat instead of low fat dairy, put some olive oil on your salad, put some honey on your oatmeal, etc. Those foods are nutritious and will help you get closer to your nutrition goals.
Losing weight is not a goal, losing weight is the result of various behaviors -- and undereating causes weight loss. But the goal is (or ought to be) health, fitness, etc. If you're trading overweight for malnourishment, are you really accomplishing anything?
I've personally suffered some pretty awful effects from rapid weight loss brought about by low caloric intake. I wouldn't recommend it. 1200 calories is really low as it is. I average 1315 calories/day including "cheat days" and I have a SLOW metabolism and I still lose weight. And I don't even do cardio at all, just strength training. I don't think I've ever met anyone with a slower metabolism than mine. So really you don't need to eat under 1200 to lose weight, unless you're 5'0" or less.
ETA: I just saw that you're a little bit older than I am -- it is true that the older we get, the slower our metabolism gets -- but the tradeoff here isn't to eat below 1200 calories -- it's to give your body a little more time to get to your goal weight. It might take an extra 4 months. Not the end of the world, right? :)
Edited by: NAUSIKAA at: 3/10/2013 (14:27)