Bmi History Average How Can I Loose 20 Pounds By April?

How can I loose 20 pounds by April? - bmi history average

I am very short and about 126 pounds. My BMI shows I am really overweight. I am a swimmer practices about 3 times a week, but have the opportunity to practice 5-6 days a week. I am 15 I know that this diet may sound silly, but with a history of diabetes and heart disease in my family that I so afraid of contracting these diseases. And I'm on spring break in April, a trip that I really want to look good. So can anyone help?