How many calories shall I take perday to lose 4 kgs in a month ?

1200 calories is the least you can take and still lose weight while not losing your msucle. If you eat less than 1200 calories a day, your body will freak out and go into starvation mode where it hoolds on to your fat while burning away your precious muscle for energy. So to lose fat and keep your muscles (muscles are what burns fat), you need to intake at least 1200 calories a day.