The myth of the Fat-buring Zone

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I see value in both low impact, low intensity cardio as well as concentrated, extreme anaerobic interval training.
Couple the above with an effective program of resistance, and you have a solid program of body re-composition.

And all of this presupposes clean food intake.

I am striving for this ideal, and as good as my results have been, I want more.

This is it!

Excellent article...my workouts are about to change!!!

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I'm confused by this comment. Would you mind clarifying?

My biggest take-home was that in the time AFTER the exercise--during recovery-- steady state doesn't do much whereas anaerobic/interval/weights does. Lovely to hear, reinforces what I'm doing anyway!

This is all very sensible to me, and I have no reason to doubt, but just curious how credible the source and author are...? Also, is the author any relation to Allwyn Cosgrove who helped design New Rules of Lifting workouts???

If you did HIIT for 5 mins and and compared that with walking for 5 mins, the percent of fat burned based on the exercise is higher for walking than HIIT. HIIT burns glycogen stores first, then fat. Walking mostly burns fat and doesn't tap glycogen because the intensity is low. But HIIT burns more overall calories.
Also by raising your RMR, you burn much more fat at rest and HIIT and other high intensity workouts do this. Walking and low intensity exercise don't.

A.C.E. Certified Personal Trainer
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Been in fitness for 28+ years and have studied kinesiology and nutrition

Really interesting... trying to get myself motivated to pick up those weights

I'm confused by this comment. Would you mind clarifying?

My biggest take-home was that in the time AFTER the exercise--during recovery-- steady state doesn't do much whereas anaerobic/interval/weights does. Lovely to hear, reinforces what I'm doing anyway!

Their reference was also outside the HIIT the article was talking about, I think referencing another myth.

Training at this lower "fat-burning zone" of say 60-70% MHR allows your body to use a majority of fat as energy, depending on fitness, perhaps 50%. But because your effort is so low, you only burn x amount of calories.

But if you just did your 20-40 min cardio at a higher "aerobic zone" of say 70-80% MHR, while you body may only be able to use 33% of the energy from fat, rest carbs, you are actually burning 1.5x amount of calories.

So just using some figures, and everyone's would be different values, but with the same principle.

Fat-burning zone for 30 min at 130 HR - 300 cal.
150 cal fat, 150 cal carbs. (50% fat)

High aerobic zone for 30 min at 160 HR - 500 cal.
165 cal fat, 335 cal carbs. (33% fat)

So while the percentage of fat burned went down, the actual amount of calories burned from fat went up, and of course your general calorie burn went up.

Just goes to show, if you only have 20-30 min for exercise - make it really count by doing higher zone, or the HIIT referenced in the article.

The fat-burning zone is great if you are at race weight already and need to train the body for 2+ hr endurance events.

If you did HIIT for 5 mins and and compared that with walking for 5 mins, the percent of fat burned based on the exercise is higher for walking than HIIT.

HIIT burns glycogen stores first, then fat. Walking mostly burns fat and doesn't tap glycogen because the intensity is low. But HIIT burns more overall calories.
Also by raising your RMR, you burn much more fat at rest and HIIT and other high intensity workouts do this. Walking and low intensity exercise don't.

Actually, just to be clear on this for folks that really are interested in getting into it.
Right on for percentage understanding, which is where most don't realize the difference.

The moments actually doing the high interval, into the anaerobic zone, would be carb burning, there would never be fat because fat requires oxygen, and the definition of anaerobic is without oxygen. The idea of HIIT is to get into that anaerobic zone.

Coming back to recovery level would be the same mixture of carb/fat that would normally occur, with the addition of the lactic acid just produced during the interval.

At total rest your system (unless insulin causes fat storage mode turned on) can do the almost total fat for energy, but as soon as you start moving, you start to approach that 50% mix.

So for folks using the HRM during HIIT, your calorie burn during the actual exercise will probably show a bit to a lot lower, because the short high HR doesn't avg out the long low HR during recovery to a decent avg that looks good.

But as you said, rest assured, you will burn more during the recovery after and all day long.

Even if you can't do HIIT, even if you can only walk, just raising the grade to something high for 30 sec, or striding really fast to that next light pole, can have great interval-like improvements.

On the other hand . . .

The advantage of training at a lower intensity for longer at first is that you can build a strong aerobic base and then after a number of months can train much longer at high intensities.

A question of short term vs. long term gain.

• Fed subjects consistently experience a greater thermic effect postexercise in both intensity ranges.

So this goes in the face of the "fasted state" training that people are doing to maximize the fat loss?

That has more to do with the fact that in the morning, before you eat, you are in fat burning mode already, that's what you were doing all night, any insulin spikes turning on fat storage are long gone.

So low intensity exercise at this time just keeps using that same mode. Your body of course starts using glucose to burn the fat at higher intensities, exactly the same as it normally would.

What probably has been noticed, is that compared to having a high carb breakfast/snack first and insulin putting you into fat-storage mode, you burn more fat first off this way.

But you can cause the same thing and have a snack first, something with much lower carbs and higher fat/protein.

I never like early morning jogs on totally empty stomach.