Sometimes it takes quite a while for something to really sink in to my tiny brain!!! And sometimes I have to consider the very outside extremes of an argument to be able to understand it completely.
So - considering the "burning fat zone" argument. It makes complete sense to me that our human energy comes from two sources - our body fat and the sugars (glycogen) in our blood. But - how, when , where and why??? I read somewhere today, that when we are at our most inactive - when we are sleeping - that our bodies almost solely use fat to provide basal energy, almost no blood sugars at all - that is why we don't feel tired or lacking energy while sleeping!! - but during the last bit of a 5K race, most of our energy is being provided almost solely by blood sugars and not fat !! That is why we feel exhausted at the end of hard 5K!!
So - at what stage of our lives do our bodies use mostly fat as a source of energy - and that is when we have a slightly elevated heart rate , more than when we are resting and less than when we are exercising strenuously . So - if we REALLY want to lose as much fat as we can when exercising, we must exercise at quite low heart rates - elevated just a little more than we walk briskly. Personally , I find it difficult to run and keep my heart rate low over a period of time - so this morning I ran/walked 10Klm at only a 30 second/30 second ratio of running to walking. This is VERY easy!! My average HR turned out to be only 116 over the period involved - 1 hour and 20 minutes. At the end, I felt that my body had had a good workout over that time - but I was very far from being "exhausted" which suggests that I could have gone on for longer. I'm going to keep on doing this at least once per week - and stretch the time out a little more. I seem to have reached a plateau as far as weight loss is concerned - hoping that this will kick it into gear again!!