Fat burning zones, a question

TheBoyBilly wrote:

Another one of those "it's already been asnwered" questions, but I can't find it:
If my fat burning zone is in the region of 100-120 bpm on a HRM, what happens when I drop slightly below or above this range? Is this such a daft question? It's me so it probably is :oops:

Hi there.

I'll save you the effort - fat burning is a marketing myth. The more exercise you do, and the harder you do it, the more calories you burn. Your body stores all excess calories as fat, so if you burn more than you eat then you'll lose fat.

Cheers, Andy

No.

No it's simpler than that:

Excess Calories = calories eaten - caloried burned.

Excess calories stored as fat and vice versa. End of story.

Cheers, Andy

In simple terms Andy is correct but fat is burnt at different rates and different efficiencies depending on HR.
It can also be dependent on metabolic rate and this can be higher after exercise in the morning.
As far as I can remember working at high hr burns off more calories and more fat than lower HR but at a less efficient rate, but can also increase metabolic rate so benefit there also.
Stay off the beer is best advice 8)

Andy, I think Hills is the answer to most general training conundrums!

I think both Andy & 3 wheeler are right.The fat burning zone is a myth - the best zone for it is when asleep! but clearly sleeping burns very few calories in total.....
Doing hill training will burn loads of calories during & after from both fat stores and carbohydrates.
Beginners start gently - eat a little less - and progress over time with increased intensity and time. For general fitness do a nice mix of exercise mostly bike 6 some running or vice versa - whatever you enjoy and can maintain - it's daily activity that keeps you healthy not slugging your guts out once a week....

andrewgturnbull wrote:

TheBoyBilly wrote:

Another one of those "it's already been asnwered" questions, but I can't find it:
If my fat burning zone is in the region of 100-120 bpm on a HRM, what happens when I drop slightly below or above this range? Is this such a daft question? It's me so it probably is :oops:

Hi there.

I'll save you the effort - fat burning is a marketing myth. The more exercise you do, and the harder you do it, the more calories you burn. Your body stores all excess calories as fat, so if you burn more than you eat then you'll lose fat.

Cheers, Andy

So when I had some fitness testing done (v02 max etc) and it showed that I burn the most calories from fat at 138 bpm and none over 152bpm - your saying this isn't true?

andrewgturnbull wrote:

method wrote:

andrewgturnbull wrote:

TheBoyBilly wrote:

Another one of those "it's already been asnwered" questions, but I can't find it:
If my fat burning zone is in the region of 100-120 bpm on a HRM, what happens when I drop slightly below or above this range? Is this such a daft question? It's me so it probably is :oops:

Hi there.

I'll save you the effort - fat burning is a marketing myth. The more exercise you do, and the harder you do it, the more calories you burn. Your body stores all excess calories as fat, so if you burn more than you eat then you'll lose fat.

Cheers, Andy

So when I had some fitness testing done (v02 max etc) and it showed that I burn the most calories from fat at 138 bpm and none over 152bpm - your saying this isn't true?

Do you really need me to answer that for you?

30 seconds with google reveals this: http://pinoyfitness.com/?p=8

Cheers, Andy

Yes, probably why I asked you...

But at an RQ over over 1, you aren't burning any fat right?

I am pretty sure that the body also tends to burn a higher percentage of fat for a given effort the longer you've been exercising up to about an hour - so if burning a greater proportion of fat was a training aim (and I'm not saying that there is any reason it should be - but some people do aim for that) then one long ride would be better than two medium length rides.

Andy, surely at high intensity (anaerobic effort for example) very little from stores is burnt since the metabolic process is too slow. Of course, once the glycogen store is replenished, could this come from body fat as well as ingested food/blood glucose?

From experience (dangerous ground here I know) I can ride at a low intensity all day, versus say a max intensity for no longer than 90 minutes. Now is a 6-7 hour touring ride going to use more stored body fat (assuming you dont stuff your face all day whilst on the bike) than a 90 minute alll out TT effort?

Last season I hardly did any low intensity rides, it was almost all TT's with a couple of high intensity rides in between. I didn't lose any weight between May and October. I lost about half a stone then up to Xmas as I started riding slower but for longer and more frequently. The TT's I rode were a mix of 10's in the week, to a 10 on saturday and a 25 or 50 on sunday. a 100 and an aborted 12 hour were in there too....

3wheeler wrote:

At low intensity you are still burning fat or rather energy you are using is coming from your fat reserves, but you won't be burning many calories, just like me sitting down writing this I'm burning some calories

Fat can only provide energy at a fairly slow rate, so when you exceed that your body needs to use the carb supplies, if you increase the intesity you are burning more calories but chances are the amount of fat being used stays the same.

It's not quite so simple though because you will usually be getting your energy from a combination of sources, however in your 'fat buring zone' a high ratio will be coming from fat.

What I have read is that at higher intensity you cannot burn fat but carbs/blood sugar. When you rest the body will replace the used carbs by releasing fat stores.

And just to add to that - this is why some people argue the fat burning zone is best for weight loss - as you need to eat to replenish glycogen stores - I've seen some people argue you will actually feel hungry if you don't - whereas you don't need to replenish stored fat as you don't actually want to replenish it if weight loss is a goal. In other words they argue you can better lose weight by fat burning and controlling your diet - if you mainly exercise intensively and limit your diet you will run out of energy.

The greater our oxygen transport capacity, the greater we are able to utilise FFA as a fuel source and the greater the rate of utilisation of FFA (v glycogen). Hence training to improve our LT and VO2Max has a direct impact on our ability to use higher proportion of FFA at all (aerobic) exercise intensities.

IOW - to "burn more fat", we need to train to become aerobically fitter. This is most effectively done at intesities at and around power at LT (~2-3hr power) and up to our power which induces VO2Max (sustainable for ~4-8 minutes).

To "burn" the most fat over time the equation is very simple - ride at the highest intensity you can sustain for the duration you have available to train. By sustainable I mean not only on that day but also sustainable in the sense that it doesn't substantially impact ability to train on following days or weeks.

method wrote:

Alex,

Could you clear something up for me, according to the testing I had done, I reached RQ1 at 158bpm and was told that I'm not burning any fat at this point and above. Is that right?

thanks.

Define RQ1

Respiratory Quotient 1

Best explination is here:

http://en.wikipedia.org/wiki/Respiratory_quotient

Basically when doing a fitness test, its one of the measurements derived from carbon dioxide production.

At an RQ of 1 (which I hit at 158bpm) all you are burning are Carbs. Which is surely why the fat burning zone isn't a myth...