Re: checking bodyfat....lowering bodyfat
When you run your body has to get energy from somewhere, right? It can be fat, muscle, glycogen, etc. The general concensus is that steady cardio at about 60%-70% of your max heart rate (I think that number is right) causes your body to get most of the calories it needs during exercise from fat rather than other sources. This causes greater overall fat loss for some people, which is what you're really looking to lose when you try to lose weight. As with most everything involved with exercise I would recommend doing some more reading on this and experimenting for yourself, though, as everyone's body works a bit differently. In my reading up on this stuff some people see better results from going all out as that can help to build some muscle, which causes longer term calorie use after working out or just due to using more calories in total to go all out, causing an overall greater caloric deficit.