In May Triathlete The article on Metabolic testing on an age group female showed she burned 360 calories from fat per hour at a heart rate of 132 and only 180 calories (ie HALF!!) at 148 bpm.I knew the proportion of fat was greater at lower intensities but to see an absolute amount of TWO TIMES blew me away.Is this for real??Does it vary between individuals??Is there any use in getting metabolic exercise testing to determine optimal fat burning zone for the few Slowtwitchers who have excess weight as one of their limiters?
What they didn’t tell you is that the fat was from fatty acids and not from adipose tissue.
This is true, but only as a percentage of total calories burned. You will still use more energy (calories) at the higher intensity (read heart rate) and will loose more “weight” if both durations are the same. Of course, at a very low intensity, it is presumed that you can go much farther, hence the LONG, slow days. I think many people misunderstand that if you are going “slow”, it needs to be LONG.
In May Triathlete The article on Metabolic testing on an age group female showed she burned 360 calories from fat per hour at a heart rate of 132 and only 180 calories (ie HALF!!) at 148 bpm.I knew the proportion of fat was greater at lower intensities but to see an absolute amount of TWO TIMES blew me away.Is this for real??Does it vary between individuals??Is there any use in getting metabolic exercise testing to determine optimal fat burning zone for the few Slowtwitchers who have excess weight as one of their limiters?
I’ve never looked closely at actual numbers and I agree that is surprising, I guess it could be possible.
Weight loss, however, is due to overall net energy balance. What matters is how many calories you burn during the day including exercise, and not necessarily the substrate providing those calories, vs. how many you eat.
riding, running, swimming, skiing, etc at a lower intensity will allow you to burn a higher % of fat during given activity. we do this not to try to burn fat per se but to increase our fat burning ability by upregulating the fat burning enzymes and train ourselves to preferentially use fat as a fuel. this is great to help us use more fat (unlimited supply) vs glycogen (not even enough to complete a marathon). ultimately, if weight management is the goal and if you only have a given number of hours to workout to burn the most amount of fat (not just during the workout) you’ll be better off to work at a higher intensity. burning more calories no matter the fuel of choice will allow you to lose more fat. if you do anaerobic work you’ll even get quite the afterburn. it just so happens that that is hard to do especially when you aren’t fit so you need to build a base. ah ha, when you get fit you lose weight and you are able to train harder and burn more calories which allows you to train harder. it’s a positive cycle. 
we do this not to try to burn fat per se but to increase our fat burning ability by upregulating the fat burning enzymes and train ourselves to preferentially use fat as a fuel.
Fat burning ability is increased by increased fitness whether you get that fitness doing low intensity workouts or sprint intervals is irrelevant to the % of fat used at any given intensity.
that was a mouthful
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