Can anyone explain something to me about the constant and frustrating advice that to lose fat you must train at 60-70% heart rate zones? Our group MTB rides are about 4 hours but consist of  2- 2 and a half hours of actual riding time. This is on single track and hills my heart rate according to my Garmin is predominately working between 80-90% for most of the time.

During 3 months of bike riding (and laterly swimming) have lost 2+ stone which is exactly what I needed to happen. My exercise  HR is above the fat burning zone but not only have I lost fat but have gained muscle. So why are we brainwashed that we must exercise at a lower HR to lose fat? The Garmin may not be totally accurate but shows very high calorie burn after my rides. A calorie is a calorie regardless of how it's burned and less calories in = weight off.

Also, if I wasn't constantly pushing myself on the bike and instead had only gone out on my own and ridden at 60-70& max HR my fitness would not have made the dramatic improvements which it has.

No one I've asked has been able to explain what appears to be a red herring. It makes me feel that working hard is somehow a failure! You're knowledge in easy to understand terms would sooooo be appreciated .

I think that Emma Silversides explained this quite well on this thread.

The bit she said that was relevant was:

The second physiological result of endurance riding is that at a lower intensity, our bodies burn a higher percentage of fat as fuel (as opposed to glycogen, the stored form of carbohydrate). Thus the popular term “fat zone” or “fat-burning ride.” Don’t be misled by this though since, in reality, your body will burn more calories at a higher intensity level (although the percentage of fat as a contribution to fuel is lower). So relatively, you burn more fat at a higher intensity (since the caloric total is higher). But the key here is that our body’s first choice for fuel during higher intensity exercise is glycogen, and exercising at a lower intensity level helps your body become more efficient at burning fat for fuel.

Basically I think this says that you are right, it just explains why the term "fat burning" zone is used.  I was always confused about it as well.

Thanks Emma. That is a very well written article.  It is quite hard to grasp. Suppose should be happy that I've knocked the fat off regardless!

Elly