What is the best way to lose weight and still be on birth control?

Exercise and diet. Exercising more than 30 mins day with moderate exertion and eating a healthy diet with lots of fresh fruits and vegetables can ensure your success towards reaching your desired weight and still being protected by a birth control of your choice.
Lose weight. In order to lose weight and keep it off, you need to make a commitment to a permanent lifestyle change. Most importantly you need to commit to a more active lifestyle. No diet is permanent. Eat 80-85% of your daily calorie needs (and count them). www.bmi-calculator.net/bmr-calculator/ try to lose at a healthy pace of 0.5-1.5lbs per week and most importantly keep that exercise level up. Good luck.