The calorie needs of a 100-lb. adult vary depending on the person's age, gender, health and level of physical activity. Consult a nutritionist or physician for help when determining the number of calories you need to maintain your weight.
A weight of 100 lbs. is healthy only for relatively short adults. According to the National Heart, Lung and Blood Institute, adults who are 4 feet 5 inches to 5 feet 1 inch in total height are within a healthy weight range at 100 lbs. Seek to maintain this weight only if it is appropriate for your stature.
Low Activity Level
If you are physically inactive, you require significantly fewer calories than your larger or more active peers. MayoClinic.com estimates that an inactive adult who is 5 feet in height needs 1550 to 1600 calories daily to maintain a weight of 100 lbs.
Moderate Activity Level
Adults who engage in moderate exercise a few times per week need more calories than those who lead sedentary lifestyles. Moderately active people who weigh 100 pounds need 1700 to 1900 calories each day.
High Activity Level
If you are very athletic and exercise vigorously every day, you need approximately 2150 to 2200 calories daily to maintain a weight of 100 pounds.