[melaniejs (OP)]

Twitter follower asks:

Is there any truth to the 'fat burn zones'? Surely calories burnt are calories burnt?


What do you think?

[toml]

Hi melaniejs,

The issue is where does the body gets its energy. You can burn calories by using the glycogen storage (limited and coming from the carbs you eat) or by using your fat storages. The ‘fat burn zones’ theory states that if your objective is to lose weight (lose fat), you should aim to target your fat storages rather than your glycogen storages; and that the best way to do that is to train at the 'fat burn zones'.

So, if you want to burn x calories, train as you wish; if you want to lose fat, train at FBZ.

Professional endurance athletes eat a lot of carbs before a run because they know their body will need it, and weight is not their problem. On the other hand, people who want to lose weight often go for low carb/Keto diet, as it restricts the amount of carbs and therefore forces the body to use fat for energy. Also, note that it is usually accepted that for weight loss, nutrition is more important than fiscal activity (although the later is also very important).

Hope it helps

[Colin2B]

The subject of fat burn zone (FBZ) causes a great deal of confusion. The important thing to remember is that the difference between FBZ and higher level activity is not the absolute amount of fat burnt, but the % used. This means that at a high level of activity you may be burning more fat, but a lesser % compared to glycogen.
Glycogen is what the muscles use, but the problem with burning glycogen is that the body’s reserves are limited - mainly stored in muscles and liver - so can be very quickly used up, probably within 1-2hr depending on activity level and training. On the other hand, fat is often available in relatively large quantities, but it takes time for the body to process it into glycogen.
The top line is that if you want to burn fat any activity level is ok, but you will have have to work for longer at a lower level or harder at a higher level. The real trick is not to replace what you have lost by having a post exercise treat eg sticky bun, any excess calories will be turned into fat.