Determine Your Daily Calorie Need
This step is going to be different for everybody and will even change for you over time. Determine how many calories you need each day to maintain your current weight, then reduce that number by 100 to 500 calories. It’s okay to start slowly with just a small reduction in calories. After all, this is a lifestyle modification, not a crash diet. If you’re too exuberant in the beginning, you might find the calorie restriction too difficult later on.
Keep a Food Diary
You’ll increase your chances of success if you keep track of all the foods you eat. You can keep your food diary in a notebook or join a diet website where you can enter your foods and the amounts into your personal (and private) account. The program keeps track of your calories and grades your daily diet for nutritional value.
And it’s free.
Re-evaluate Your Diet
When your weight goes down, your calorie requirement will decrease, and you’ll need to adjust your calorie intake until you reach a healthy weight. Remember the goal of a low-calorie diet is good health; don’t let your weight get too low (below a BMI of less than 18.5). If your BMI gets too low, you need to increase your caloric intake a bit.