Would like to lose 20kg.?

You want to lose 45 pounds in 3 months without diet or exercise? I guess that just leaves surgery or you could become a crack head and be too high on drugs to care about eating, there may be some unwanted side effects with this diet method though.

you mean you don't want to follow a diet where you eat certain foods but you do understand that you have to eat less?
eat every other day. Eat what you want one day and the next drink water, lemon water, zero calorie diet sodas, unsweetened tea and/or coffee.
if you eat a normal amount or even a little more than normal you will be cutting your calorie intake in half by not eating the next day. I've been stuck at a weight for a couple of years and i read about a guy who lost 100lbs in 6 months by eating every other day and i'm giving it a try. Since i get to eat a normal amount every other day i don't really feel all that hungry on the days i don't eat.
today i'm not eating. tomorrow i will eat a whole pizza plus whatever i choose to eat for breakfast.

Losing 20 kg in two or three months is not realistic. You would have to run like two marathons a day to achieve that.