Dropping pounds is all about the numbers. First, find out how many calories you need to maintain your current weight based on your age, lifestyle and other factors at www.calorieneedscalculator.com. Then, through diet and/or exercise, create a 500-calorie deficit per day. For example, if you need 2,000 calories per day to maintain, aim for 1,500 to lose weight. Want an easy way to keep up with your calories? Track your meals and exercise for free at www.fitday.com.