[header] How to safely lose weight (for teen girls ) [title] Calculate your bmi. [step] There are lots of websites out there (even apps for your iphone, ipod touch, and ipad) that will calculate your bmi. Your bmi stands for body mass index. 
It will tell you whether you are severely underweight, underweight, average/normal, overweight, and obese. Make sure that you use a bmi calculator that factors in age and height! Calculate your weight now, and if you are in the normal range, you shouldn't lose more than a few pounds.