One problem you may be encountering is you may be eating too little calories. For most people, at about 1000-1300 calories/day the body actually starts going into a "starvation mode" and shutting down some of its functions which actually lowers your metabolism since your body is trying to protect itself and is saving all the energy (calories) for vital functions such as for your heart, lungs, and brain and nervous system. Most nutritionists I've talked to or articles I've read suggest 1500-1700 calories a day for weight loss and if exercising regularly along with dieting as much as 2000-2200. WHile you will lose weight with 1200 calories/day, you may be sacrificing nutrients, such as vitamins and minerals, and you may be breaking down muscle by using protein for the energy your body needs just for day to day tasks. I would suggest trying to up your intake to 1500 calories/day to start, but also making sure that those extra calories are good foods and not just junk and if trying to build muscle make sure you are getting a decent amount of protein (about .8 to 1.4 grams protein per kilogram of bodyweight depending on your activity level is all your body can really use, so also don't be too worried about extra supplements and all.) The best way to burn fat to get lean is a combo of diet, cardio to burn calories, and weight training/toning exercises to build lean muscle. I hope this helps and good luck achieveing your goal!