Daily Calorie requirements for a 13 years old girl

Dear Ask The Doctor: I am a 13 year old girl, 5 foot 2 inches and 87 pounds. I know i'm underweight, because i only take in 800 - 1000 calories a day. I want to excersise, but i have been known to 'over-excersise'. How much should i excersise a day to maintain my current weight?

Dear Caitlyn: According to recommendations by the USDA (dietary guidelines for Americans), depending on height, weight and activity level, a normal 13-year-old girl should consume between 1,400 and 2,200 calories each day. If you are dieting, you can consume fewer calories and still have a healthy diet, just have to make sure that you get sufficient macronutrients, which include protein, carbohydrates and fat, as well as essential vitamins and minerals. If you are planning to working out or playing sports, you can consume more than the USDA-recommended calorie number and still be healthy. If you do physical activity during the day that's comparable to a 1.5 to 3 mile walk at 3 to 4 mph, the USDA recommends you consume 1,600 to 2,000 calories. If you want to learn more exact figures for your body, meet with your doctor or a dietitian, or use an online calorie calculator. If you play sports or do physical activity similar to walking at least 3 miles at 3 to 4 mph, the USDA recommends 1,800 to 2,200 calories. Try to make  sure your diet is healthy and  do not go  below 1200 calories a day ,  which  is the bare minimum, at 13 you need more than that just for your body to grow properly, so maybe you would want to keep  the calorie requirement around 1600 and exercise actively.