Q: I do weight training 4 times a week .On Sunday i have a rest day.Is it ok to eat less this day as i dont go to gym(if i would i would burn more calories then right?).Also,how long after a weight training does your body continue to to burn fat and build muscles?

A: I prefer to keep the diet the same even on off days because, as you mentioned your body continues to recover and burn calories on off days. I also find keeping the diet the same just easier and less hassle :) But you are correct that you burn somewhat fewer calories due to actual physical activity, so if you prefer you can decrease the calories slightly on off days (maybe by 200-300 calories, not more).

As to your second question, your body can easily take a week recovering from heavy weight training sessions and there's some evidence that it still continues for as long as one month! Most of the recovery however definitely happens in the first few days to a week.