Fitbit Charge question...Fat burn

flippy1234

This may be a stupid question but, where it shows heart rate on my fitbit, changes to either cardio with a number or fat burn with a number when I am working out. Does this actually mean I am burning fat at that moment?

mmapags

Yes in a general sense. We are always burning some combo of fat and glycogen. At lower intensity more fat and a little glycogen. As the intensity goes up, the more glycogen comes into the mix.

It is always some mix. So, the zone thing is kind of misleading. At rest, or sleeping, we burn mostly fat.

NorthCascades

Those labels are meaningless. You lose the type of fat that's important by being in a calorie deficit.

heybales

It's useful (if the zones based on HR are correct) if you are training at a level where a recovery day (fat burning zone, used be called more accurate Active Recovery zone) is needed after a more intense day of training.
Or if doing intervals and after going all out or very hard, you know you need to drop it back down to that level.

Unless you are doing a program or very knowledgable about the matter, that is unlikely to ever be the case.
Do what feels sustainable for what you are doing.

Usually after observing a few workouts or reviewing the HR later - you'll have memorized 2 or 3 HR numbers that are meaningful to use no matter what zone they may happen to fall in.

Azdak

You are always “burning fat”. You are always burning some mixture of carbs and fat. The body does not switch to “fat burning mode” on and off. Those labels are gimmicks, based on the incorrect suggestion that the fuel burned during exercise has an effect on stored body fat (i.e. fat loss).

It does not. Fuel burned during exercise has no direct effect on stored body fat loss. Body fat is lost or gained because of an overall calorie deficit or calorie surplus.