What Is A Fat Burning Zone?
I was recently presented with a question on the ‘Fat Burning Zone’ as part of a forum discussion and my response ended up being an article. So, I thought I’d post it here in case someone else finds it useful.
The tone is a little rambling and it may not be all that structured, but I was just letting go, because it’s one of those ‘truisms’ that just keep appearing again and again and one I thought there was more common knowledge about these days.
The original post read:
“I have been fat burning for 2 months now and seem to be wondering sometimes if I am wasting alot of time for nothing. I have lost about 1st in this time from 18.7 down to 17.7stone, and need to get to 15 stone. I was in a bad accident 1yr ago and when I came out of hospital with my shoulder and leg in casts I continued on my normal diet of pasta etc and not taking into account the amount of cal’s I am not using compared to what I did before my accident and this made me put on at least 2 1/2 stone over the year. I knew I shouldn’t be eating as much but it was so hard not to due to the boredom.
The problem I have is 2 of my friends have gave me conflicting info and both of them are fitness instructors. I am 28 and 1 of my friends says I should be doing 60% of my max H/R for 1 hr a day which is about 115-116 beats per min…… well i now do 1hr 45 a day at this rate and I do feel the difference….. AND…
My other friend says i should be working at around 135-140 for 1hr for the best fat burning
I know how the fat burn process works etc, like you only burn sugar for the 1st 20 mins then u burn fat but I don’t know what H/R’s to stick to”
My Response read:
I’m going to try to answer this, but talk of a ‘Fat Burning Zone’ really drives me crazy because it adds confusion where there should be none (as you have clearly found out).
First, there is no magical heart rate where you suddenly start burning fat. You are always burning fat and carbohydrates (or glycogen) in every activity. What shifts is the balance between the two (or the focus). The slower and more laid back the pace, the more your body uses fat as its primary fuel source. As the intensity of your activity increases your energy source switches from Aerobic to Anaerobic and the fuel source becomes primarily carbohydrates (I’ll stick with that term as it is the macronutrient you consume and so will recognize it more freely – I don’t want to over confuse with the actual internal process).
However, even when carbs become the primary fuel source, your body will still be burning fat, just a much higher percentage of carbs.
The so called ‘fat burning zone’ is the zone that you work at where you are burning the most calories before reaching the point where this change in emphasis occurs (and it’s usually – though not always – around 60-70% of your Max HR).
There are several problems with that though:
1) The max HR calculation of 220-age is a huge generalization. Even the person who came up with it has since been quoted as saying it was just a theory and he didn’t expect people to take it so literally. That calculation can be vastly off. First off, women can usually get the heart rate higher than men during exercise (if at the same level of fitness).
Also, someone who is physically fit can raise their heart rate much higher during exercise (safely) than someone who is new to physical fitness. Therefore, if you are going to aim for this magical zone it would probably be best to use PRE (Perceived Rate of Exertion) as your guide [on a scale of 1-10 (10 being flat out) how hard are you working?] and you would aim for around 6-7/10 which is slightly out of breath but still able to hold a conversation without the sentences getting broken up.
2) Is burning fat during exercise the best solution? – Have a think about this. Your body will react to the demands you place on it. So, for example, if you lift weights, what you are actually doing is breaking down muscle. Your body then reacts by building that muscle back stronger than before in order to cope with that demand.
If you burn fat, therefore, what does your body do?
It tries to cover that demand for the future by trying to store more fat. Now if you keep pushing for longer each time and continue to train, that may not be a problem. But you can’t increase your output indefinitely. There are only so many hours in the day. And when you stop increasing your output level your body’s improved fat storing ability will catch up with you. And if you were to stop altogether, you would probably end up putting on more fat than you had to begin with. Therefore, if fat burning is your goal (as opposed to endurance running) then wouldn’t you be better teaching your body to store the nutrients you want it to and to let it realize the one thing it can do without is fat?
As a comparison – Imagine the physiques of an Olympic 100m sprinter and compare to that of a marathon runner. Which would you prefer to achieve?
Most people go for the sprinter, because they look more ‘toned’. That is because, whilst long distance runners are ‘skinny’ they still generally have quite a high body fat content and what they have lost is actually muscle tissue. The reason is that is what makes them more efficient long distance runners. (muscle weighs more than fat, fat is easier to carry around and is an acceptable fuel source, so that’s what is sticks with).
3) Calorie Balance – When it comes down to it, the only thing that matters when burning fat is the calorie balance. If you are burning more calories than you are consuming you will lose weight (and fat) if you are consuming more than you burn you will not (and may add weight). Therefore, the more calories you burn the better. Now, if you were to go out and go for a nice gentle stroll for half an hour the percentage of fat burned over carbs would be huge. The ratio is greatly in favour of fat burning at that level. If, however, you were to go and bust a gut sprinting for half an hour you would be burning more carbs than fat.
Does that mean you are more likely to burn more fat walking than sprinting for the same period? Absolutely not! In fact, even though you are burning more carbs than fat whilst sprinting, you are still burning more fat than you would be walking, you are just burning even more carbs. But over all, what you are doing is burning vastly more calories and that is what will help you achieve that deficit.
My last point is going to be about weight though – you say that you have lost 1stone and NEED to get to 15stone. Why? What is so magical about 15st?
Are you competing in a boxing competition?
Are you a jockey?
Are you doing an activity that has a weight restriction?
If yes, then your comment is perfectly valid. However, if it is because you were 15st in the past when you looked good, that is not a valid reason. If you stuck your arm in a tractor’s wheel and ripped it off you would probably lose the weight you wanted to, but I’m guessing that’s not the look you are going for (But then maybe I’m just out of touch with the ‘in look’ these days).
However, if you were to add a little muscle (say 5lbs) and drop another 15lbs of pure fat, I think you’d find you’d look a lot better than you wanted to. But you will only have lost 10lbs more. The thing is, weight is not the issue – the amount of fat on your body is (remember, muscle weighs more than fat). I refer you back to the 100m sprinter and the marathon runner physiques. The marathon runner will weigh much less than the sprinter, but which physique looks healthier and more ‘toned’?
So, in summing this up, my suggestion is to forget about fat burning zones.
When you go to train, with whatever you are doing, do it with an intensity befitting the results you want. If you are looking to burn fat and you have 40mins available, then work at an intensity that is befitting 40mins of HARD WORK. Push yourself and don’t leave anything in the gym (or on the track). If you have 20mins work even harder to squeeze the most out of your session. If, on the other hand, your goal is to run the London marathon, then train for endurance, forget the scales and just work on your technique and progression.
If you train hard and your diet is right you will get the results. At the end of it all, results are all that matters. Find what works for YOU and do that, even if it goes entirely against what the ‘science’ says ‘should’ work.
I hope that is of some use to you.
Hopefully that clears up a few issues and maybe clarifies some of the confusion regarding the subject and will allow for a more informed choice when it comes to your training regime.
Thanks, as always, for taking the time out to read my ramblings and I truly hope you are finding them useful.
What is a Fat Burning Zone
by Mark Tiffney
What About You?
What do you find works best for you?
Do you prefer to feel it out? Are you a strictly weights and diet person? Or are you a self- confessed cardio bunny and proud?
Let’s discuss in the comments below.