Without any qualifiers, that's absolutely meaningless. Per minute, high intensity will be more effective than lower intensity work. But you can't keep it going for anywhere near as long.
It is of course for a given exercise time - but then most people interested in losing weight don't want to spend the time exercising that would mean they couldn't keep going at a higher intensity. Meanwhile, high intensity is very useful to raise the metabolism, which does mean you'll carry on burning energy well after you've stopped exercising. The point is that the "fat burning zone" is a myth from the POV of weight loss - there is no point at which you stop burning fat, or even at which you decrease the amount of fat you burn. The only thing people have to consider is not to exercise so hard they can't keep going.
Yes I acknowledge there is a point to lower intensity work - I went through this one years ago where I spent a couple of months going really slowly limited by heart rate, and taught my body to exercise at lower heart rates. However it's not the way to go if you're purely after weight loss - and indeed if you are already doing enough of that, then doing more is less effective than doing some more intense stuff.