We have all seen it on countless cardio machines and some may have questioned its validity. There is (nearly) always a mode/program you can select called some variation of "fat burning". This is usually linked to heart rate (measured by the machine) but not always.
What is the "fat burning zone" and what science backs its claims that it is better than the other programs for burning fat?
Sources
During this n=36 study, the optimal fat burning zone - i.e. the point at which one has the highest fat oxidation rate - occurred on average at 54.2% VO2max.
However, the great variance between the participating individuals makes it hard to pinpoint this as the fat burning zone.
Interestingly, this article by Alan Aragon, suggest that while fat burning is seemingly higher during low-intensity cardio, post-workout fat oxidation was higher after high-intensity cardio, and that if one measures the effects of the two after a 24-hour peroid, it evens out.
It also gives some insight into the difference between pre-workout meals, and lack thereof.
It then states the following, which I will quote directly to avoid any errors caused by interpretation:
In long-term studies, both linear high-intensity and HIIT training is superior to lower intensities on the whole for maintaining and/or increasing cardiovascular fitness & lean mass, and are at least as effective, and according to some research, far better at reducing bodyfat
Discussion
I think these findings only serve to strengthen what we already know about the fitness industry; individuality is too prevalent to really make any foolproof claims about which regimen is best for the goals we aspire to.
Especially, anyone who claims to have a be-all end-all piece of information should rarely, if ever, be taken seriously.
Only you, by trying both/all regimens, can discover what works best for your particular body, which is surprisingly different from everyone else's.
Suggestions
If you want results, you should start by picking the regimen which makes you most excited. Not only does it seem like it will be equally effective as the others, but it might be even more so if you enjoy it, and are able to keep motivation high.
Try one regimen for a few months, and measure your progress as best you can. Then you can try another regimen for the same period, and see how you feel about the execution and the results.
Even if the most enjoyable one isn't the most effective over a short span of time, it will likely keep you motivated for longer, and yield the best long-term results.
It should be a simple matter of energy output. Spending half an hour at 200W should have the same effect as a whole hour at 100W. So it all comes down to how much time you want to spend exercising and how exhausted you want to feel afterwards.
Relatively more energy will come from fat during low intensity workouts, but the type of energy storage used doesn’t matter. Your body will just use more of the muscle’s glycogen storage during high intensity workouts and you’ll have to eat to replenish those afterwards. There is no magic way of doing exercise without energy expenditure.
