Cardio is great for loosing weight, although weight lifting burns more calories than running. Lets say you run for an hour and you burn 600 calories. Once you step off the tredmill you stop burning those calories. When weight lifting you burn calories while lifting and depending on your body you can burn calories for up to 72 hours later. I would personally preffer to do both. Get the best of both worlds. But, it is said you burn more calories from lifting than running.