No matter what type of diet you follow, to lose weight, you need to burn more calories than you take in each day. For most overweight people, cutting about 500 calories a day is a good place to start. If you can eat 500 fewer
calories every day, you should lose about 450 g a week.
Burning fat is simply using fat as a source of fuel. This doesn't mean that you are dropping weight though. Your body is always burning a little bit of fat, even at rest. And oftentimes you replace this fat with the calories you eat - causing no loss in overall fat mass.