Cardio vs Fat Burn

[dfox]

Under the exercise tab there are three different "time in heart rate zones,"  peak, cardio, and fat burn.  Between cardio and fat burn what is the difference and which one is better?  Thanks!

[Dominique]

Check what are heart-rate zones from this help article:

https://help.fitbit.com/articles/en_US/Help_article/1565#zones

There are different benefits in spending time in each of the zones.

[WavyDavey]

@dfoxif I had to choose, I vote for cardio. Fat burn sounds great, but the number of calories burned is much lower than cardio. Cardio zone is more efficient, and has a greater effect on heart health.

If a person is only getting time in the fat burn zone, it might be time to step up the intensity a bit. In the end, you'll get and want time in both zones, as @Dominique stated.

[emili]

hey @dfox - it also depends on your current fitness and ultimate goal. I do not spend every work out in cardio because that is not my goal any longer. However, when I was losing weight and endeavoring to improve my cardio score, I was in cardio everyday for varying lengths of time. these days I spend time in cardio three out of the six days I work out. If I am running I spend at least 45 minutes in cardio/peak per run. If I do high incline walk it is cardio for at least 50 minutes out of the 60. Lifting or walking I stay in fat burn for most of the time... I never hit cardio or peak.

[Slimfit145]

Which is better for weight loss. Cardio or fat burn?? 

[SunsetRunner]

@Slimfit145 there's no rule. It is more complicated than you think and than Fitbit shows. Fitbit simplified the whole thing to just 3 zones but there is a lot more to it. Most of the athletes who practice zone training know more than just three zones. A distinction between "fat burn" and "cardio" ( which are not really zones used by athletes ) is quite simple. If your major source of fuel is fat, then you are in "fat burn" zone, otherwise, you are in "cardio" and higher. But even being in the cardio zone you still burn fat. Here's quite a good breakdown with advice on how to train for a particular result:

https://www.verywellfit.com/heart-zone-training-3432619

There is no big difference really in an amount of fat burned during low-intensity and high-intensity exercise within the same timeframe. For example, during one of my runs, I spent 40% in threshold zone, and 55% in anaerobic zones ( all in all over 80% of my MHR ). In total within 20 minutes burned 278kcal and approx. 10% of that is fat ( actually little more but not significant ). Let's say 27.8kcal comes from fat. Then, a moderate walk for 20min ( however, I managed to elevate my heart rate slightly ) burnt 153kcal from which 19% is fat. So we have 29kcal. 2.2kcal difference in fat, so actually less intense exercise was slightly more effective in burning fat. But overall there's a difference of 125kcal and here more intense exercise takes a lead. So it really depends. I prefer to do more intense exercise with rest periods when I let my HR to drop to quite low levels so I can catch my breath.

Real fat burn happens by diet not exercise. Again, let's do some numbers. 1g of fat is 9kcal, so technically if you burn 9kcal of fat you burn 1g of fat ( it's not that simple we can make it look so ). So in 29g ( my 20 minutes of walk ), you burn maybe 3 grams of your total weight? Doesn't look that great, does it? I don't take here into account many other factors. As I said, I simplified things quite a lot.

More about zones you can find for example here:

http://www.mastersathlete.com.au/sidebar/endurance/training/heart-rate-zones/

In this article, they specify 7 zones, not 5.

[Slimfit145]

Wow those articles do mention a lot of zones. Thanks for the info. I’m not training for anything just wanted to shed quite a bit of body fat. Noticed that all my zones are 90% in cardio according to Fitbit.

[SunsetRunner]

@Slimfit145 you may also check this article:

https://www.unm.edu/~lkravitz/Article%20folder/fatfacts.html

It is a more scientific explanation of how we burn fat and what difference the intensity of exercise does make. The conclusion can be simplified to:

- If you are already very fit, then more intense exercise does a better job when you want to burn fat

- For less fit people it may be a struggle to go with higher intensity exercise and low intensity may bring better results.

[Nicqui]

Well explained - thank you!  Makes sense!

[YachatsMike]

The two zones line up to the intensity levels from HHS in the Physical Activity Guidelines.  It says that a person  should  get at least 150 minutes of moderate or 75 minutes of vigorous minutes of physical activity per week.  After that, more is better.  They measure activity by heart rate and the zones, moderate and vigorous, line up almost exactly with what my fitbit calls fat-burn and cardio.

[YachatsMike]

The zones and goals pretty much like up with the Physical Activity Guidelines from HHS. (The platform won't let me post the link but it's easy to google)  I see that the new app update even changed the name of the zones (moderate, vigorous) to match.  There is much in the guidelines worth reading, especially in Appendix 1, as you set your exercise goals for the week.  My personal goal is to at least double the  basic guidelines for Active Zone Minutes each week.  I do that by maximizing my time in the Vigorous Zone.  I let the steps, distance, and calories take care of themselves.