Can body weight training work comparing it to the actual conventional weight training in a gym?
Body weight training is effective up to a certain point. Just like any exercise using resistance you will build muscle but the amount of resistance can not be increased if you are only using your body weight. You can build strength by increasing the number of repetitions but once you build up to above 20 reps the exercise becomes more of an aerobic exercise which is more for building the cardiovascular system than an anaerobic exercise for building up muscle mass!
You must keep adding more weight over time in order to build up muscle. The muscle will adapt to the amount of resistance that is put on it if given enough rest.
I am not saying that body weight training is not good but there is a limit to how much resistant you can use. Push ups and sit ups and deep knee bends are all good exercises if you choose to do them. You can get into good shape with this type of training but free weights and machines provided much more resistance and will build much more muscle over the long haul. I think what most of this boils down to is what are your fitness goals and what do you what to gain from them. Either way is good and you can't go wrong if you stick to a regular program. Here is a video I found that shows how to do effective body weight only exercises. Click here to view the video!