Losing weight is a simple equation. If you burn more calories than you eat, there is no way to fail. First estimate how many calories you are burning each day using the Calorie Calculator. To lose weight you need to create a calorie deficit, meaning you have to burn more calories than you eat.
Healthy weight loss is defined as no more than 1-2 pounds (0.45-0.9 kilograms) per week. To lose 1 pound (0.45 kilograms) in a week your deficit has to be 500 calories per day (consistently).
This means you have to eat 500 calories less or burn 500 calories more. You can also do a combination by eating 250 calories less and burning 250 calories more. To lose 2 pounds (0.9 kilograms) a week, your deficit needs to be doubled to 1,000 calories per day.
The most important point to remember is consistency. Even going out of your calorie range for 1 or 2 days can put you off course.