It is best to have an athletic build but the exercise will help you to lose weight. Your ideal weight is related to your height so you need to know your height and then when you have your weight to can refer to a chart which shows your body mass index. This will tell you if you are under or overweight for your height. If you are very over or underweight it is best to correct now as it can lead to some health problems later on. I hope that you can enjoy your dancing and keep fit as well.