Can somebody tell me how much weight will i lose on primal/paleo diet?

No: There is no sound nutritional reason to use this diet, but if you choose to do so it's likely you'll lose substantial weight during the first few weeks. This happens with almost any major diet manipulation. Unfortunately, almost everybody gains the weight back. Best course is a balanced, low-calorie diet including all food groups that can be sustained for life plus vigorous regular exercise.

A substantial amount: It depends on how much you weigh now. For example, a patient of mine who was 425lbs lost 80lbs in 9 weeks. Much more common is a patient losing 20 lbs in the first two months as they don't have near as much to lose. However, if you need to lose 30-50 total, for example, most people who go into nutrional ketosis will lose closer to 20 lbs in 2 months based on my estimation of patients I'v seen.