text: info please!? ok so i havent ever been worried about my weight until in health we were checking bmi and stuff. im 98 pounds and i am 5 3 and i am 14 years old.my bmi is 17...you're supposed to be 18 or over and i am supposed to weigh 115 pounds.  im not anorexic or bulemic. i dont eat very much at one sitting, but i eat often. i swim or play softball for 2 hrs, three times a week. my friends and my mom tell me to eat more and that i dont weigh enough. is this bad? the bmi can fluctuate to a point. it sounds like you're doing all the right things with your diet and exercise. don't worry too much about it...you are still growing and could just have a high metabolism rate. if you started to lose weight or not gain weight properly,then there would be cause for concern. as long as your energy level is fine and you continue with your regular routine,don't get too worked up over it.