Ok, so I figured out what fat burn vs fitness was on my HR monitor. My numbers from the last workout were:
fat burn - 1:27
fitness - 36:37
In other words, I only spent 1 minute and 27 seconds in my fat burning zone. The remaining 36 minutes and 37 seconds, I was conditioning my heart and increasing my fitness level.
What this means to me:
There is a lot of debate about the 'fat burning zone'. According to where you find your information, the fat burning zone is somewhere between 60 and 70 percent of your max heart rate. And to find your max heart rate you subtract your age from 220.
According to this calculation, my max heart rate is 184. Therefore my fat burning range is between 110 and 128. This is hard for me to wrap my brain around. Because I just don't feel like I'm "working out" if my heart rate isn't at least in the 150s.
The theory is you burn more fat in the fat burning zone than you would doing a higher intensity workout. But overall, the harder you work, the more calories you burn. And so if you workout for 30 minutes at a higher intensity, you would end up burning more calories overall than if you just stayed in your lower fat burning zone. And in the end, it's about intake of calories and calorie expenditure. BUT, if you burn 50% fat during 30 minutes of exercise in your fat burning zone and only 40% fat during the same 30 minutes of higher intensity exercise, where are the extra calories being burned coming from if not from fat? I am confused. Are you strictly burning off carbs from your last meal? Or worse, muscle? How does this work? And what about after burn? Doesn't recovering from higher intensity exercise burn off more calories? Here's a chart from about.com explaining calorie burn and fat burn at different intensity:
| Low Intensity - 60-65% MHR | High Intensity - 80-85% MHR | |
| Total Calories expended per min. | 4.86 | 6.86 |
| Fat Calories expended per min. | 2.43 | 2.7 |
| Total Calories expended in 30 min. | 146 | 206 |
| Total Fat calories expended in 30 min. | 73 | 82 |
| Percentage of fat calories burned | 50% | 39.85% |
On the other hand, since I have been exclusively using high intensity exercise and not seeing one iota of difference in my body composition, that might be telling me something. There might actually be some truth to that fat burning zone, thing. Maybe I should try taking nightly brisk paced walks for a few weeks and see if that theory holds water. But in any case, at least I know that I am really doing something wonderful for my heart and overall fitness.
1 comment:
its as clear as mud to me charlotte!!! i'd love to try the whole fat zone burning thing but what if its a waste of a weeks exercise? what about calories in -v- output? when i do hiit on cross trainer its usually 1minute at 10 kph then 30 seconds at 24 kph and repeat. i swear my heart and lungs are going to explode by the end of a 30 second interval. what if im only getting fit and not burning off any of my fat arse?? im not interested in my fitness levels until im lookin' smokin' hot with no jiggles - then i'll worry about how fit i am!!! maybe ive got it wrong - is this why im not losing the fat as quick as i think i should be??????? what to do? let me know if you research any more :)
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