text: how many calories would you have to eat to gain a pound? i took several classes in highschool that covered nutrition. but  i vaguely remember any of it. i'm guesing it differs in different people based on age, gender, race and so forth. so if it were to be young adult female, how many calories would have to be consumed to gain a pound or atleast close to a pound? 3500 calories are in one pound. for example, if you consume an extra 500 calories/day in a week you can gain one pound (500 calories x 7 days = 3500 calories = 1 pound). the reverse is true for weight loss. if you reduce your caloric intake by 500 calories/day for a week you can lose a pound in that week.