The quickest way to lose weight is probably a low calorie diet and an intensive exercise regime.  You often see people who go on challenges where what they can eat is limited to what they can carry and throughout the challenge they have to do a great deal of exercise, will lose huge amounts of weight in a very short amount of time.  Obviously this is not possible for the average person, but you can learn something from their challenges in that a reduced calorie intake, or even the same as you have now, combined with intensive exercise will result in fast weight loss.