How many calories do you need?

To get a rough estimate of how many calories you need in a day to maintain your present weight, multiply your weight by 13, if sedentary, and by 15, if moderately active. You need to add more calories for rigorous exercise.

To lose or gain weight, subtract or add 500 calories through diet and exercise. For example to lose about a pound a week, decrease your calorie intake by 250 calories and increase the calories you burn off through exercise by 250. Walking one mile briskly in 15 minutes burn approximately 100 calories.