Hi, new here! Just lost 20 lbs and looking to lose 10 more

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Hi, I just started MFP this week-it's a great website for keeping track of everything! I actually wish that I had known about this site a year ago when I dropped 20 lbs. (I used to weigh 182 at 5'5", now I hover around 162-165)

I'm a freelance designer which requires many hours on the computer and when not working, I'm job hunting-so I have a very sedentary life style. I was really pleased that despite this lifestyle I was able to lose 20 lbs! However, I want to lose 10 more and the last 10 has been extremely difficult. I did drop down to 159 at one point, but it was with 3 months of undereating (about 800 cal/day.) I started feeling sick on the 4th month, getting dizzy every time I stood up, and just generally feeling weak. I hated that feeling so I increased my portions to make the 1200 cal/day and of course gained back some of the weight. I felt better, but now I have the fat back on my belly and every meal I feel stuffed to the point of throwing up (and they're only 300 cal meals!) I've been doing toning exercises and cardio, but I'm not seeing much result except for increased strength and stamina. (Which is a great feeling!)

I'm going to keep eating clean at 1200cal/day and keep up the cardio with the toning. Just wondering if I need to increase it or if it's something else? Also, a good friend of mine told me that it's possible that birth control pills make it even harder to lose weight. Any ladies have thoughts on this?

Looking forward to participating in this community and nice to meet you all!