To lose one pound of fat, you need to create a caloric deficit of 3,500 calories. Therefore, to lose one pound a week, you need to create a caloric deficit of 500 calories per day. However, its important to note that this can vary depending on your body, how much you exercise, and other factors. Its generally recommended to aim for a safe rate of weight loss of 1-2 pounds per week, which would require a daily caloric deficit of 500-1,000 calories. Its also important to ensure that your daily calorie intake does not fall below 1,200 a day in women or 1,500 a day in men, except under the supervision of a health professional, as eating too few calories can deprive you of needed nutrients and endanger your health.