Fat Burning Zone?

Q. I recently joined a large health club and they recommended that I pay for some heart rate testing. They explained that I may be working out too hard and not burning fat. They suggested that I buy a heart rate monitor from them and make sure that I stayed in my "fat burning zone". Does this sound right to you?

I really thought that this ridiculous exercise prescription had gone away with thong leotards. It all stems from studies that support that you burn a larger percentage of your calories from fat at a lower heart rate. While this may be true, the "fat burning" heart range is so low that you are not burning a lot of overall calories. Would you rather burn 50% of 300 calories (150) or 30% of 900 calories(300) from fat? Of course, 300 fat calories makes more sense and because the intensity is higher, it is going to take you half as much time to burn the extra calories. Here is a post from Alwyn Cosgrove explaining this theory in a different way:

Homeostasis is the property of a living organism, that regulates its internal environment so as to maintain a stable, constant condition.

When you don't drink enough water in the short term -- often the body retains water. It attempts to maintain homeostasis by counteracting the stresses we put on it.

When you drink a lot of extra water - your body excretes more water to maintain balance.

When we weight train -- we actually break down muscle tissue. And the body responds by building new muscle. It attempts to maintain homeostasis by doing the reverse of the stimulus we placed on it.

When a male takes supplemental testosterone -- the body shuts down it's own production in a bid to maintain homeostasis.

When we immunize children against disease -- we actually inject them with a small dose of that disease. The immune system recognizes the vaccine as foreign, destroys it, and 'remembers' it. When the virulent version of an agent comes along, the immune system is thus prepared to respond. In order to prepare the body to defend against a disease - we expose it to the disease - and it responds by doing the opposite - it destroys the disease.

In almost every situation I can think of, the body tries to maintain homeostasis by "doing the opposite" of the stimulus.

Now we know that while you are doing it -- low intensity exercise burns primarily fat.

Higher intensity exercise actually burns more carb stores than fat.

But in every head to head comparison, high intensity exercise results in more fat loss than low intensity exercise - even though the more intense work may burn a lesser percentage of fat during the exercise session.

Burning glycogen results in a larger amount of fat lost than burning fat directly.

The body responds by "doing the opposite"...

Break down muscle to grow more muscle. Burn glycogen to lose more fat.

Rick Mayo