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03/07/2003 at 18:32

I'd like to lose some fat.

My local gym said that 'high intensity' running was useless, as it doesn't burn any 'fat calories' whatsoever.
I was told that I'd only burn 'fat calories' if I exercised at a much 'lower intensity'.

However, a couple of books that I've read say that what the gym told me was a misconception. One book quoted the following example:-

'High intensity' half-hour run:-

Total calories - 600;
Percentage of fat calories - 40%
Fat calories (600 x 0.4) - 240

'Low intensity' half-hour run:-

Total calories - 300
Percentage of fat calories - 70%
Fat calories (300 x 0.7) - 210

As you can see, the percentage of 'fat burning' calories is greater on the low intensity run. However, the total number of calories to which this percentage is applied is of course much fewer, meaning that fat calorie consumption is lower than with high intensity runs.

Who should I believe - the gym or the books?

03/07/2003 at 18:51
From personal observation the best way I have noticed myself and some of my friends lose weight (fat) is by walking 40mins to 1.5 hrs every day in total.

This basically consists of walking to and from work 5 days a week.
03/07/2003 at 19:03
Is that in one go or throughout the day
03/07/2003 at 19:30

As someone who is shifting 3-4lbs a week currently, I have asked the same questions.

Personally I go for the low intensity option. The equation you quoted missed a crucial detail - you can't do high intensity runs every day!

The key (or, rather, one of them) to "turning on" your fat burning mechanism is the consistency of regular low intensity exercise.
03/07/2003 at 20:04
Lightening - As far as I am aware, those formulae that you have quoted above appear to be correct. At the higher intensity, a lot of the calories burnt are glycogen calories.

Heres the crux.

With the 30mins high intensity, ur body's metabolism will remain a good bit higher than with the low intensity for a long time after the exercise. So in other words, the formula above gives 240kcal (fat) for high intensity. Overall, this will be a good bit higher if you take into account the increased metabolism.

So in short, you will shift more fat with high intensity workouts, but TAKE AT LEAST A DAY OF REST (or low intensity/recovery workout) BETWEEN HIGH INTENSITY WORKOUTS so that your body can recover the lost glycogen.
03/07/2003 at 20:05
btw, just noticed that the formulae above do not take into account your body weight. This will affect the actual result but it is correct in theory.
03/07/2003 at 20:11
Not convinced RR! What you say is true as far as it goes, but that does not mean it is the best way to lose fat LONG TERM.

The best thing to do is to teach your body to naturally burn as much fat as possible at higher and higher speeds. That HAS to be done by LOWER intensity running.

Your sums are right when looking at a day or a week, but that is not the issue at hand.
03/07/2003 at 20:16
No - the books are right. Also, doing some resistance work will help you develop more lean muscle tissue and therefore turn you into an efficient fat burning machine when you're doing nothing at all. Vary the intensity you work out at for best results
03/07/2003 at 20:21
I believe that a calorie burnt by exercising is one less calorie stored in the body and its doesn't make that much difference if its burnt "high" or "low" intensity. You must have to work out pretty hard to burn 20 calories a min, better to have a mix of low intensity and high intensity in the gym. I alway work out in the lower range as I count it as an easy day.

Running burns the most calories.
03/07/2003 at 20:23
No - the books are wrong long term. The person burns more fat - yes - but only burns 40% (assuming these percentages are right - highly unlikely). He remains an ineffecient fat burner. He burns more fat that day but loses long term. The other runner burns at 70% (alegedly) becomes a more efficient fat burner and does the faster workout later but burns say 55% fat because they have taught their body to burn fat efficiently. The tortoise beats the hare - watch the big picture!

Also why put on muscle to burn fat? If you want to burn fat, teach yourself to burn fat with lower intensity runs and then when you have a decent base do more. Be patient. If you want to run fast you don't want extra muscle mass to carry around. Agian, it is true as far as it goes, but that does not make it the best option in the long run.
03/07/2003 at 20:26

What you say is true to a point, but WHAT calories you burn is as important as how many if:
1) You want to lose weight long term
2) You want to run efficiently
Which I imagine is the whole point of this thread...
03/07/2003 at 20:31
Hmm. And here's another point. ANY run/waddle/plod/jog for me is high intensity! And I'm sure I'm not alone. :o)

I'm sure that once I'm a gazelle rather than a wombat I can differentiate between puffing and sweating a bit, and puffing and sweating a lot.

But for now - I'm just glad I'm burning calories.
03/07/2003 at 20:34
As I understand it all that matters is that you consume less calories in fuel than you use. Whether its from high intensity or low intensity exercise does not matter.

While it is true that the body can use fat as the intensity of exercise is gets lower from say 70% of max HR it does not matter that glycogen is used for high intensity exercise as after the exercise the body will break down fat while you rest to replace the glycogen stores. Always provided ofcourse that it does not get it all from eating.

What is true is that while you are losing weight you will geenrally have lower glycogen levels than you would have normally and hence you will find it difficult to do long high intensity sessions which require glycogen while low intensity would not be a problem as it can be supplied directly from the body's fat stores.

I have lost 4 stone over three years by doing a mixture of all three approaches in six week bursts with a rest in between coupled with eating a bit less than normal.

1). High intensity running/cycling/swimming
2). Weight sessions to build muscle mass (which consumes more calories even when resting)
3). Quite a bit of walking everyday, between an hour or two at a good pace.
03/07/2003 at 20:35
I can run "efficiently" for hours, rubbish at running fast.

I am prefectly happy with my weight, not skinny, not fat.
03/07/2003 at 20:36
I'd have to disagree with you Pantman, the books are right the gym is wrong (I realise your argument isn't the same as that of the gym which is obviously talking rubbish). I take your point about low intensity but following that to a conclusion you burn a high percentage of calories as fat lying down but that isn't a good way to get thin.

It's an interesting debate though. Can you spell out your argument in more detail? I take it you are saying steady running causes the body to adapt so that it metabolises fat more efficiently and so will continue to burn a higher percentage fat at higher heart rates? But if that is the case aren't you just using less glycogen - so when you do eat instead of replenishing glycogen stores your body will just lay it down as fat?

You can probably tell I tend to lean towards the calorific in vs burnt argument.

03/07/2003 at 20:36

too right! Started the same way. Used a HR monitor to r/w/p/j up to a medium intensity and then walked to lower regions of fat burning HR range and then r/w/p/j again - keeps the HR in the right fat burnign range t/out.
03/07/2003 at 20:38
I think its best just to get a mixture of high and low intensity long term - the low intensity help to build fat burning efficiency and the high intensity burns more fat per workout, which will increase as the low intensity increase fat burning efficiency
03/07/2003 at 20:40
also, theres nothing wrong with a bit of muscle work to increase endurance and for burning fat, the extra weight shouldn't be a problem unless ur doing way too much weight work or ur putting it on the wrong places
04/07/2003 at 00:56

Thanks for an intelligent and thought out response!

Yes I am saying that teaching your body to burn fat means you will burn it at higher intensities. But to achieve that properly you need to do it EXCLUSIVELY but ONLY for a period. This is similar to what Lydiard was doing and is what many top athletes (who need no weight loss) also do.

Consider Mark Allen who won the Ironman 6 times (I think) - he never went over a lowish aerobic pulse for 4-5 months of the year! 150bpm , I think it was. Initially he found that to get his pulse that low he was running 7:30 or 8 min mile pace - and this was AFTER he was already one of the "big 4" in triathlon racing at 5:15 pace! He was maxing it out all the time and burn neat carbs! After an extended period of do NO training over 150bpm he managed to get his pace up to 5:30 pace while at that pulse - he taught himslef to burn fat. Anecdotal? Yes, but the science backs it up too.

The question is short term or long term? If you want to lose weight LONG term, if you want to peak LONG term and if you want to stay healthy LONG term, then fat burning is the way to go.
04/07/2003 at 08:19
Interesting, I suppose the idea of focusing on one thing exclusively would fit in with periodising training - which is popular in lots of sports.
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