However, this computation doesn't take into account exercise or your activity level. For example, since someone who exercises regularly can bring in more calories and still be at their maintenance weight, their BMR would be higher. Other issues like genetics, age and the amount of body fat/muscle you have can also affect your caloric needs.

Q: How can I track my caloric needs?
A: An easy way to give yourself a personalized assessment of your caloric needs is to keep a detailed food and activity journal for a week or two before you begin dieting. You can obtain a calorie counter at any bookstore or use a calorie counting tool like the one at The USDA National Nutrient Database.

Record everything you eat and drink every day. Calculate your calories on a daily basis and record your weight at the end of each week. If your weight is the same as when you started, then you are at your BMR. If it is higher, then you are eating more than your BMR. (Both scenarios assume that your activity level is consistent.) This is the starting place for you to begin cutting down on those calories coming in.

Now's the time to begin planning your meals with their caloric content in mind. Working your way down a few hundred calories at a time will be the easiest way to adjust to lowering your calorie-intake. You can do this quite "painlessly" to start with. For example, simply cutting out a few colas per day your normally drink will save you hundreds of calories.

Q: When will I see results?
A: Any calorie deficit you create will eventually lead to results. As a rule of thumb, 3,500 calories is equal to one pound. For example, if you eat 250 calories per day fewer than your maintenance rate requires and exercise enough to burn an additional 250 calories each day, you will lose approximately one pound per week.

Additional Resources:
Keeping a Food Diary
Food Diary Print-Out