I'm not understanding this "heart rate zone" thing..

jgilbey

I don't understand how keeping my heart rate 120-140 will be fat burning?? When i'm on the elliptical/ treadmill I easily get my HR up to 170-180s?? And I do it for about an hour. If I kept my HR around 130s I'd feel as if I wasn't doing very much- hardly breaking a sweat.

Info: I'm 23. Resting HR is 73 (just took it). According to my age and the calculations I've read about my "fat burning zone" would be 118-135? Could someone explain how that would work? And what I'm doing to myself if I keep exercising with a HR of 170s for an hour?

ZugTheMegasaurus

It's based on a misconception of the studies about it. Basically, at lower intensities, the percentage of calories burned from fat is greater than at higher intensities. The problem is that it burns far fewer calories total for the same period of time. So, for example, if you do a half hour in the "fat burning zone," you might burn 100 calories and 50 of them will be from fat. If you do a half hour at a high intensity, perhaps only a third of the calories will come from fat, but you might burn 300 total. So in order to lose weight, you're better off aiming for the greater total number.

I just found this article about it (I don't remember where I originally read it, but this one looks okay: http://www.active.com/triathlon/Articles/The-Myth-of-the-Fat-burning-Zone.htm). There's a lot more information out there if you look it up.

ironman1431

Zug is absolutely right. It all has to do with old exercise physiology science.

When your heart beats at certain levels, you use different energy systems (aerobic, anaerobic, creatine phosphate etc.) If you exercise at a low heart rate, the energy/fuel for your exercise is primarily adipose (fat tissue). However, this energy system/fuel is extremely efficient, so a little energy from fat goes a long way. You end up burning fewer calories, but the calories you burn are those from fat. You're better off exercising at higher rates of exertion (look at the Karvonen method for more accurate HR). That way you burn more calories during exercise, but also burn more once you are done exercising as you'll be in EPOC (exercise post oxygen consumption) to a certain degree, where your body is burning more calories even at rest to make up for the oxygen expelled during your exercise.
The most accurate resting HR is in the a.m. before you get out of bed.

ehs5mw

The fat-burning zone is not a myth at all. If you actually read the article linked above, you will see that the above poster is only half-right. The fat-burning zone just means that you burn a higher percentage of fat within the calories that you burn compared to what you would burn at other heart rates.

All this means is that you need to decide if your goals are more about weight loss or fat loss. If you want to just lose weight, it would be more efficient to exercise at a higher heart rate. If you want to lose more fat compared to muscle (not overall fat but percentage of fat), you should target the fat-burning zone.

Labeling it as a myth is pretty unfair and even dishonest, in my view.

ZugTheMegasaurus

Labeling it as a myth is pretty unfair and even dishonest, in my view.

It's certainly not a myth when you're talking about what it actually means. But it's generally viewed as a myth because people DON'T understand that. Most people look at the icons on the cardio machine that say "FAT BURNING ZONE" in big red letters and think, "Oh, well I want to lose weight, therefore I want to lose fat, therefore I should do that." That seems to be the impression the OP was getting. This is one of those situations where context matters in characterizing it as a myth.

Rayjewls

If time is a factor then high intensity is best. When your heart rate is high during your workouts you are really conditioning your heart to work better...cardiovascular health...and you are burning more sugars then fat. Lower intensity burning more fat. So...if I were you I'd just mix up my days with high and low intensity days and maybe intervals days also...just have fun....and get your without in. that's all that really matters.

suziecue66

Just do high intensity and low intensity so you get the benefits of both.

What I've read: To burn the most fat exercise at 74% maximal heart rate - 220 minus age times 0.74. For 23 yr old its 145.7

(I'm trying to remember where I got that 74% figure - so haven't got a link).

BrianSharpe

All this means is that you need to decide if your goals are more about weight loss or fat loss. If you want to just lose weight, it would be more efficient to exercise at a higher heart rate. If you want to lose more fat compared to muscle (not overall fat but percentage of fat), you should target the fat-burning zone.

Labeling it as a myth is pretty unfair and even dishonest, in my view.

So your body only burns fat & muscle? What happened to the glycogen stored in your liver & muscles while exercising?

When you exercise at higher intensity you're burning carbs & fat and, yes it's a higher proportion of carbs but it's still a higher number of calories overall which leads to fat loss.

The fat burning zone is really only of interest to endurance athletes training their bodies to burn more fat than carbs or people who want to use it as an excuse not to break a sweat,

ehs5mw

No, I was trying to keep it simple since it appears that this poster wanted a very basic answer and then was told immediately that it was all a myth.

We could get down in deep in the details if you really wanted, but you are incredibly far off in your belief that this "zone" is only important to the two specific groups you mentioned. You do realize that your generalizations are off-base, right? You do realize that many casual exercisers are given target heart rate zones to optimize their fat loss ratio, right? This inherently leads to making it "of interest" to people who want to lose weight efficiently in terms of fat loss compared to their muscle loss, regardless or glycogen stores. You are either not giving the complete picture or not possessing the complete picture, and I'm not sure which it is.