Optimal HR Zone for Burning Fat

[Splash]

Hello all.

(This is a general fitness question and may not specifically relate to bike riding but instead can relate to any form of exercise... So, power meters are not part of this query...)

I recently read that too high HR zone does not burn fat. Why is this?

I always thought that a higher heart rate would be better for burning off fat because of the higher intensity required to sustain this higher heart rate...

Which heart rate zone is best for burning fat and why?


Note to ALL - please DO NOT contribute / post on this thread if you cannot be specific to the thread title.


Splash

[echappist]

Originally Posted by Splash

Hello all.

I recently read that too high HR zone does not burn fat as much as Lower heart rate zones.

Why is this?

rate of energy oxidation. Exercise is essentially the burning of energy (which requires oxygen); higher the intensity, faster the energy burning required. If we are just straight up burning things, we get CO2 and H2O; however, your body requires intermediates between the initial oxidation of energy source (either fat or sugar) and the final release of waste as Co2 and H2O.

HR is an indicator of rate of oxygen consumption. Rate of lipid oxidation is a lot slower than rate of sugar oxidation, as the former requires quite a fewer more steps to become suitable for energy utilization whereas the latter does not (this assumes steady state, aerobic efforts). At high enough intensity levels, energy supplied from oxidizing fat alone can no longer meet demand, thus requiring the oxidizing of sugars in your body. At even higher intensity, even the oxidization of sugar is no longer enough to keep up with demand, and you essentially end up partially oxidizing sugar. The byproduct of the partial oxidation is pyruvate, which your body converts into lactate. You can do this type of energy utilization for only so long before too much lactate accumulates, forcing you to drop the intensity. When the intensity has dropped sufficiently, the body converts lactate back into pyruvate, and pyruvate then gets further utilized for energy via aerobic process.

I always thought that a higher heart rate would be better for burning off fat because of the higher intensity required to sustain this higher heart rate...

Which heart rate zone is best for burning fat and why?

Splash

Fat burning zone is red herring. The following chart shows you why. At the end of the day, the colloquial fat burning (i.e. losing weight) is mostly dependent on energy in/energy out, and the more energy you burn, the more weight you lose.

The fat burning zone (~55 % VO2max) is so termed because this is the zone at which energy derived from fat burning per se (and not contribution of fat burned as percent of total energy burned) is the greatest. It's a middling endurance intensity, which can be kept up for 4-5 hours. However, in term of energy burned/time spent, it's about 2/3 of what can be sustained for 40-50 minutes. If you want to maximize the portion that is burned as fat, you actually go less than 55% VO2max.

Takeaway message is that at the end of the day, it's (primarily) how much energy burned that matters, not how much fat burned per se that matters

[Splash]

Thanks for the detailed reply.

What % of VO2max (and over what duration of time) would you advise for maximising the portion of energy that is burned as fat?

For weight reduction driven exercise, is the optimal time of day to exercise - for maximising the portion of energy that is burned as fat - deemed to be after awaking from sleep AND before any food calorie/energy intake?

I have read that this is the best time because your body has been working throughout the night processing any ingested food from the day before and so any energy burned (during exercise after waking up) will be mostly from existing body fat storage and not much from any food calorie/energy. Is this correct? Something to do with insulin levels...?

What does "other fat sources" represent on that bar chart you provided?



Splash

[John H.]

What is your end goal?

Are you looking to improve your cycling, or reduce your body mass?

I bet you will say both- but is one more important?

It is not as simple as locking in to a "magic" zone and burning way more fat.

For cycling fitness- a balanced program that is polarized with all zones (at the right times and in the correct does works best).

For weight loss- the bottom line is that you need to eat less than you burn over a long period of time.

[SoCalSteve]

Originally Posted by John H.

What is your end goal?

Are you looking to improve your cycling, or reduce your body mass?

I bet you will say both- but is one more important?

It is not as simple as locking in to a "magic" zone and burning way more fat.

For cycling fitness- a balanced program that is polarized with all zones (at the right times and in the correct does works best).

For weight loss- the bottom line is that you need to eat less than you burn over a long period of time.

Congratulations! You just wrote the shortest, most effective weight loss book ever!

I hope it’s a best seller and makes The NY Times best sellers list.

One last piece of weight loss advice ( Like anyone asked for my advice )...it’s 80%/20% in terms of importance. Guess what is 80%. Eating less or exercise?

[Splash]

Thanks Guys.

Yes. I am very much aware of the eating less, exercising more line.....Can we perhaps move past that for the purpose of this thread.........??

This is not about cycling per se, that is why I specified this in the OP. I have put on weight from minimal activity over last few months. So I want to lose weight before I get serious in cycling again. Cycling will assist me losing this weight and so wil many other things like diet and other forms of exercise. So, for this moment, my end goal is to lose 15kg. Improving Cycling technique, power, etc will come later...for the purpose of this thread, I want to learn more about Identifying optimal HR zones and nothing more.

If you want to contribute to this thread, can I please ask that you be specific to the OP and thread title and not derail the thread by deviating away.

Thank you


Splash

[floxy1]

In my experience V02 intervals are optimal for burning fat.

[Gummee]

Originally Posted by Splash

So, for this moment, my end goal is to lose 15kg. Improving Cycling technique, power, etc will come later...for the purpose of this thread, I want to learn more about Identifying optimal HR zones and nothing more.

As has been said: there's no 'magic bullet' for burning fat.

Your best bet to lose that 15kg is ride, ride, ride. Keep the eating at the same level you're at now, and the weight will come off.

IME the more you do, the faster things happen.

M
The guy that's lost 20kg riding bicycles

[Splash]

Thanks Flo x y 1

Can you possibly elaborate on how you have used VO2 intervals for burning fat in your experience?

Durations, %levels of VO2, etc?


Gumme e - re-read post #6.


Splash

[regularguy412]

Disclaimer: I'm not an Exercise Physiologist.

I would add to the aforementioned, that some consideration needs to be given to the subject's age. As I'm nearing the big SIX-OH, I find that riding more and eating same amount doesn't quite cut it like it used to. This is from the guy that took 6 years off the bike, gained 80 lbs and then lost 70 of it,,, all that between the ages of 40 and 50. So it can be done, but as I get a little older, I find that using the same formula to become fitter/lose weight doesn't quite work like it used to.

So now I'm just trying to hold steady,, even though I've put about 25 of that 70 back on. Work,,, ya know,, sux.

Mike in AR

[John H.]

It is a low number- like 60-70% of VO2 max hr.
Every step up in zone burns less fat, more glycogen.

But again, higher zones burn more total calories during the workout and keep metabolism at a higher level after a ride- so it is not as simple as what you are asking.

To simplify this- find an eating plan that allows you to lose weight. Then add back in enough calories to fuel whatever riding you are doing.

[Splash]

Thanks John H.

Interesting information regarding HR zones.

Does fat burn more efficiently when exercising after a long period of sleep and no food ingestion?


Splash

[John H.]

Not more efficiently- but you may be able to pull it off if intensity is low-ish and ride does not get too long.

It works for some but it may not be the best way to train.

Like I have said, and others have chimed in- there is no "magic bullet".

Originally Posted by Splash

Thanks John H.

Interesting information regarding HR zones.

Does fat burn more efficiently when exercising after a long period of sleep and no food ingestion?


Splash

[weisan]

Originally Posted by John H.

To simplify this- find an eating plan that allows you to lose weight. Then add back in enough calories to fuel whatever riding you are doing.

I got the first part down (lost about 7 pounds in 10 days), still trying to figure out the second part. I skipped dinner yesterday and my last meal was at 2:30 pm. At today's group ride, I basically ran out of fuel at the 50 mile mark despite eating regularly during the ride. Apparently, I went too much into a deficit that normal breakfast and on-bike feeding couldn't make up for it fast enough.

This is all new territory to me. I have never consciously engaged in a weight loss regimen until recently because weight was never a major issue for me on top of the regular exercise that I do. However, I realized as I get older that it's becoming harder to keep this up just through exercise, I actually need to watch my intake as well. Over the last 10 days I have cut my daily calorie intake by 20-30% and the effect is almost immediate. I also started doing upper body workouts. My goal other than weight loss is to see that whole middle section goes down, way down.

[sdrides]

Originally Posted by echappist

At the end of the day, the colloquial fat burning (i.e. losing weight) is mostly dependent on energy in/energy out, and the more energy you burn, the more weight you lose.

That's the basic idea. Early AM "fasted cardio," as the bodybuilders call it, does burn more fat and more calories because of the biochemistry involved, and because it essentially puts your body at a deficit to start the day from which you will have to work harder to recover unless you can take naps at work. That said, it also depletes the muscles themselves more, so I would say that from an overall performance standpoint it's not as great as it might seem. If you just want to look good then give it a shot, but honestly cycling doesn't cut it for looks! If cycling performance matters, then it's better to eat before you ride.

Mainly the best way to burn fat is to ride your bike below lactate threshold for as long as possible, eat healthy, and drink plenty of water. Since you're probably short on time during the day, throw in a couple interval sessions here or there to increase the deficit and have some fun.

Final note: don't conflate body weight with body composition. Working out in a dehydrated and/or fasted state will often give the appearance of weight loss that same day (both in the mirror and on the scale), but I would argue that it's not the same thing as the genuine weight loss you're seeking, which is actually a change in body composition. Water weighs 8 lbs. per gallon...