The appropriate weight for a 12-year-old girl who is 5 feet 1 inch tall is between 110 and 120 pounds. This is consistent with a healthy weight for a person of this specified height and age.
Average children between the ages of 9 and 13 need to consume 1600 to 1800 calories a day to maintain a healthy weight. If a child is extremely active, the recommended daily calorie intake increases to an average of 1,800 to 2,200. The calorie intake needs to consist of a balanced diet of whole grains, fruit, vegetables, dairy and lean meat. Weight gain happens when a child takes in more calories than the body exerts.