Andy,
I think the devil is in the details.
I think Jarery's approach is probably best for people with a limited time who can sneak in an hour during the day. In that case, a more intense workout of 80% is probably a better way of losing weight than a less intense workout of 60%. But that is assuming that one does not gobble up more calories after the intense work out then after the fat burning workout. Of course, some people do a perfunctory workout and then reward themselves by eating something very fattening with the result that exercising stimulates weight gain!!! They are better off just sitting around.
Pat