do low intensity cardio mate on the treadmill.for me and loads of others its the best at burning fat.i dont know what sorta treadmill you have but has it got incline capabilities on it?at my gym i just go for an incline of 7.pretty steep and a pace of 4 which is near a fast walk.do this for 30-40 minutes.basically wana keep your heart rate between 125-140.you dont have to run like hell to shift weight.i sweat just as much doing low intensity stuff.