So this works like this: bench your body weight and right after run 5 kilometers, is this training regime something you can do three times a weeks for weight loss? since I love running and benching .
this sounds similar to cross fit or boot camp type workouts. 5K running is quite a lot of running though, i would encourage you to make sure you hydrate and are not too exhausted before lifting so you don't over do it
Anything that increases your heart rate will help burn fat. I am not sure about only doing bench though. What about the rest of your body?
I think a better idea for fat loss is to weight train 3-5 days per week with intensity and low rest periods. Add in 3 days of cardio and get your diet locked in.
I think its best to separate weight and cardio sessions. You are giving your body mixed signals by trying to do both at the same time.
Weight workouts - hey we need to get bigger and more musclar so we can lift this heavy weight
Cardio workouts - hey we need to be lighter and smaller so we can run faster
I would either do your cardio workouts on separate days or at different periods then your weight workouts. You could do cardio in the morning and then lift weights at night or vice versa.