Fantastic to hear you plan to get your body weight down. This really is the way to go if you can make it work.
The fully gold plated outcome is to get your weight down to around 13 stone and keep it there. This will not only give you access to a much wider choice of aircraft to fly it will also drive down your risk of losing your license in the future due to medical problems.
Obesity – your BMI is 36 which puts you well into the obesity category - can result in heart disease, high blood pressure and diabetes. Even at 15 stone your BMI is 28.5 which indicates you are seriously overweight but in a very much better position than being 19 stone.
Keeping the calories down and the exercise up is the way to go. Don’t try to get it all off at once but look for an average reduction of 2 to 3 pounds a week. To get to 15 stone plan on it taking around 30 weeks.