You only need to be healthy enough to begin exercising at a level appropriate to you. 
I coach 1 to 1 and small groups of up to 4 people.
1 hour.

It depends of course how many kg/pounds you wish to loose. It also depends on many fitness sessions you can do a week and if you can follow an appropriate diet. 

Both training and diet needs to fit your needs without draining you out of energy. In-fact loosing weight too quickly can cause people health problems; at Beltramo Fitness we therefore strictly avoid extreme diets and rapid fat loss. We look after your health by helping you to loose fat 100% safely.

Beltramo Fitness offers you a safe and optimal solution that fits you. Many average people can take between 3 and 12 months to reach their desired body weight.
Provided that you are healthy and able to follow the exercise program, between 3 and 5 sessions a week are ideal. Two weekly sessions are the basic needed.