You need to burn 3,500 calories more than you take in to lose one pound of weight. This translates into a reduction of 500 calories per day to lose one pound in a week, or a reduction of 1,000 calories per day to lose two pounds in a week. A calorie reduction can be achieved by either eating fewer calories or burning more calories through physical activity. A combination of both is best. See CDC's Balancing Caloriesto learn more.
Note: It is generally considered safe to lose weight at a rate of one to two pounds per week, but you should check with your healthcare provider or an RD before starting any weight loss program. RDs are health professionals who are trained to provide counseling on nutrition and eating habits. They can provide personalized dietary advice, taking into consideration your health status, lifestyle and food preferences. The Academy of Nutrition and Dietetics can help you locate an RD who specializes in your health condition with Find a Registered Dietitian.