Is your comments on your HR about weight loss training zones or a concern for your health?

My understanding about fat burning is this. In lower zones you burn mostly fat. As your HR increases your body does not stop burning fat, rather, it begins to add an additional fuel source to suppliment your fuel needs. You will still burn the same amount of fat. Look at it as if you run on regular grade gas and when needed you get a nitro blast added into your carb.

If you look at an overall perspective of a single said ride. Higher intensity burns more calories. So if you ride for one hour and burn 200 calories or the same hour and burn 600 calories which one would do your body the most good?

If you look at High Intensity Workouts (HIT) in general terms. They say that by ramping up your metabolism from a HIT training session you will burn more calories in the following 24 hours than you did in the training session.