some say that low intensity is the best to lose weight because at this intensity the body can use the bodyfat as energy source, but do this for more than 30 minutes, the first 30 minutes the body use the glycogen produced from last meal or the glycogen stored in your muscles. At low intensity you still can breathe easily and bring enough oxygen to the heart. High intensity, the body use glycogen more than fat storage, and your heart doesn't receive enough oxygen. I prefer high intensity because I'm intense
but it depends which days. anyway you can do low intensity all day long by walking, running, keep moving, going to the grocery store, working, etc.